INTRODUCTION

The Seljuk period (5th to 6th century AH) is one of the most influential periods in Islamic art, especially architecture. In this era, due to the peace and political stability of the Seljuk territory, artists had better conditions and were able to create several works and various developments and innovations such as the use of various moulding techniques, the use of tiles and bricks in this period, caused architectural decorations. It makes Seljuk era more diverse and extensive than the early period of Islamic architecture. (Kiani 2000, 54; Cattelli and Hambis 1997, 9-21). The hadith "God is beautiful and loves beauty" (in Arabic: ان الله جميل و يحب الجمال) indicates the absolute beauty of God. In the Holy Qur'an, we read: "He is Allah, the Creator, the Maker, and the Former. To Him belong the Best Names" (in Arabic: هو الله الخالق البار ء المصور له الاسماءالحسنی). God is the source of goodness and beauty; So the artwork, as a creature of the artist, indicates the existence of the Glorious God and His beauties by showing beauty, because it deals with beauty (Fahimifar 2009, 75). This crystallization of God's absolute beauty in Iranian-Islamic art, while narrating, is full of ornaments and its aesthetics based on the principle of decoration and beauty is the main manifestation of this art.

One of the most important architectural decorations in the Seljuk period is the brickworking of the Taj Al-Molk dome, which in terms of its unique species and brick layouts, is one of the most beautiful and richly decorated elements of brickwork. Since the manifestation of divine beauty has been the main subject of Iranian Islamic art and architecture throughout history and one of the ways to create it is with the help of decoration, so the connection between decoration and beauty is undeniable. The link of this connection lies in the consensus of simile and purification to ensure the emergence of the Divinity (God), which, as a means of manifesting monism and divine perfection and beauty, has had a transcendental reflection in the decorations of the architectural works of this period. Therefore, studying and understanding the relationship between simile and purification in the philosophy of decoration is necessary for knowing Iranian art, which has appeared in different historical periods with different features and forms and is manifested in the form of decorations in art.

Behind these decorations, there are different concepts that have their roots in religious and mythological beliefs, culture and politics of these tribes. These concepts have been represented in a naturalistic and symbolic way and have gradually continued as a motif in the Islamic period. According to some thinkers, some of our realized artistic examples are either expressions of wisdom such as mosque architecture or direct expression of mysticism or a process as a result of which Islamic ideas come into existance as a result of the years of Iranian experience. Thus, the body of works of the Islamic era is in fact an objective manifestation of the hidden role of works synonymous with "content and the inner". These two roles, while independent, are completely compatible with each other (Avani 1996, 76; Nasr 1991, 12; Masaeli 2009, 26).

Religion, as one of the historical foundations of human beings, is the same as beliefs and the way of life, and human has never been able to live without religion and art. On the other hand, art is not a mere abstract thing, but a reality that has appeared and manifested in all aspects of life and completely intertwined with human life. In fact, Iranian art has long been closely related to the spiritual customs derived from its religion, and the religious reality of the artist has been the most important factor in shaping art. Art becomes the language of the artist's deep wisdom and the manifestation of his/her most beautiful spiritual and mystical feelings. Iranian architecture is a process of science and art, taste, trust, faith and special skills and is one of the greatest manifestations of the emergence of reality in Islamic and religious art. Relying on spiritual teachings, it has been able to manifest pure Islamic wisdom with the language of symbol and gesture in the material body of the external world. Islamic art begins with existence and ontology. In this respect, the artist is similar to a philosopher or mystic who is not content with mere reflection of the world and refers to the world of general facts (Rahnavard 1999, 51; Sadri 2008, 70; Fahimifar 2006, 113).

SIMILE AND PURIFICATION IN RATIONAL PHILOSOPHIES (ILM AL-KALĀM) AND ISLAMIC MYSTICISM

Simile and purification are two terms in the sciences of hadith, Kalam and Islamic mysticism. They are one of the important and historical issues of human rational and theological thinking after proving the Divine Essence, acknowledging the impossibility of reaching its essence (reaching the completeness or integrity of something), giving a brief idea and concept of the Divinity. They are two terms in Islamic rational philosophies about the attributes of God. "In a term, simile means the comparison of one thing with another thing of a different kind; and purification means to take something away from something" (Zuzani 1966, 213-214). In the term of Ilm al-Kalām, simile is assimilating God in essence or attributes to creatures and attributing the attributes of creation to the Creator in such a way that, for example, the essence of God, like human beings, has body, flesh, blood, hands, feet, eyes, ears and other organs; He shakes hands with the servants and He can be seen; The attributes of God are like the attributes of human; His knowledge and will are like the knowledge and will of human and His words are of letters and sounds. On this basis, this action is called simile and the simulators are called tenor. The people of simile believe that God has a place and He sits on the throne and steps on a chair and has heads, hands, and organs and created man in his own form. But among the thinkers of Ilm al-Kalām and Islamic mysticism, simile is the embodiment of God. Purification is the consideration of God as purified from any human attribute and simile, attributing the characteristics of people to the Creator (Ardestani 2017, 91). Purification is the belief in the purity of God from creatures and the denial of the attributes of creatures from the Creator. The speakers call it purified because they believe that God is the One that has neither body nor appearance, form, and limit, but He, as mentioned in The Qur'an, is a being who is nothing like Him, and in the term, He is purified from defects and possible attributes (Shahrestani 1986, 105; Khayat 1975, 59-60). Simile and purification is one of the most important and complex topics in mysticism, and one of the central issues of the mystical school of Muḥyiddin ibn Arabi. They are neither pure similes nor pure purification; In other words, they are both simile and purification; Because they have not completely rejected both the purification and the simile, but have tried to bring the two together. The consensus and union between these two words has been proved analytically in Ibn Arabi's writings, and as he considers the simile to be a limitation of God, he also calls purification the conditioning agent of the essence of the Glorious Truth. He states that "in the eyes of the people of truth and in front of God, purification is the concretized essence of limitation and delimitation, and in the eyes of God and whoever does so is ignorant or rude" (Ibn Arabi 2008, 68). Ibn Arabi uses purification and simile both in the common verbal sense and in the specific sense of the term. In the specific sense of the term, purification means unboundedness (release and abandon), and simile means limitation. Regarding this meaning, from Ibn Arabi's point of view, purification is mixed with simile, and for this reason, he considers correct knowledge to be knowledge that is comprehensive between purification and simile. Therefore, from his point of view and the followers of his school, purification and simile are complementary to each other, that is, it is not possible to imagine and realize one without the other, and the essence of God is absolutely needless, and the world of being, in the manifestation of the name of Truth, are all a multitude of divine names and attributes. He states that "the Divinity is a special manifestation in every creation; so He is the Apparent (the Manifest) in every idea or concept and He is the Concealed (the Hidden) from every apprehension, so He is the manifestation of the hidden name; therefore, His relation to what has appeared from the form of the external world is the soul’s relation to the form, and whoever abandons the religion of simile and denies it, he/she also restricts and limits the Divinity. Therefore, only those who consider the world as the form and identity of the Truth gain true knowledge because they can consider the phenomena of existence with a metaphorical view as the external name and consider the hidden of the Truth as the soul of the world based on the purification approach. This ontological view of Ibn Arabi is a clear example of the monotheistic verse of Sura al-Hadid that "He is the First and the Last, the Manifest and the Hidden" (verse 3), so from his point of view, purification means the manifestation of God for Himself and in His essence; which is outside the domain of cognition, because it is a domain in which no one has a way except God. On the other hand, simile includes His manifestation in the forms of external creatures and states of existence, and true knowledge is the sum of these two words, which has been done by the Prophet of Islam (PBUH). In other words, the Divinity (the Haqq) is manifested in the forms of the world and the manifestation in the state of names and attributes (Ibn Arabi 2008, 51; Ibn Arabi 2006, 244; Saffari Ahmadabad et al 2018,100). Ibn Arabi says that the best representative of the Divinity is His word, because in the Holy Qur'an, simile and purification are included but in the text of each other. He considers the best example in this regard in the verse 11 of Sura al-Shura "Nothing is like Him, and He is the All-hearing, the All-seeing" (In Arabic: لَيْسَ كَمِثْلِهِ شَيْءٌ ۖ وَهُوَ السَّمِيعُ الْبَصِي).

This verse contains two parts, each of which is somehow gathered between purification and simile as follow: this verse, while proving a "similitude" for the Divinity (if we do not consider it redundant ک in كَمِثْلِهِ), that it is a "simile", but denies the existence of like for "like Him" and thus through the first, the existence of "like him", which is "purification", is denied. Moreover, while the Divinity is described by all-hearing and all-seeing (simile), but all hearing and seeing (according to the use of He: in Arabic هُو) is limited to the Divinity and is denied from others (Purification). Other verses such as verse 84 of Sura Az-Zukhruf “It is He who is God in the sky, and God on the earth, and He is the All-Wise, the All-Knowing” (in Arabic: وَهُوَ الَّذِي فِي السَّمَاءِ إِلَٰهٌ وَفِي الْأَرْضِ إِلَٰهٌ ۚ وَهُوَ الْحَكِيمُ الْعَلِيم) also indicate the combination of purification and simile. It confirms that the Divinity, while being Transcendent from the material and abstract, is present in both with the position of divinity. It can be said that the Iranian-Islamic artist, with emphasis on the themes of Islam, contrary to the pictorial tradition of other Abrahamic religions, neither depicts the role of God in a purified way, nor deifies the image of the Truth in a purely metaphorical view. Rather, by using the allegorical attitude that is the result of the consensus of concepts of simile and purification, he/she conveys the spiritual spirit to the constituent elements of his/her work and refers only to the beauties of real existence, God's creation and His names and attributes.

In a purified view, he/she protects himself/herself from the challenge to God's creation. In a metaphorical view, he/she considers the beauty of the world to provide a place for the emergence of his/her artistic creativity in unity and harmony with Islamic themes. By eliminating the presence of his/her individuality, he/she avoids challenging the essence of the Divinity and does not imitate and represent the concretized existence and creates a beautiful work of art consciously and carefully with the awareness of the unique divine creation in the state of combining the themes of simile and purification. For this reason, as Burkhart says, "Islamic art, in the light of this awareness, has a special purity and sobriety and an non-individual quality, and this makes the Muslim artist always remind himself/herself of his/her creator" (Burckhardt 1991, 28). These two words are rooted in the Qur'an more than anything else. In the Holy Qur'an, the Divine Truth calls Himself with attributes such as "the Hearing, the All-Seeing and the All-Knowing" (The Holy Quran, Sura al-Shura / 11, al-Nisa /58, al-Nisa /148, al-Baqara /244, Saba /50, Al-Imran /38, Fatir /31 al-Mulk /19) that are compatible with the attributes of the servants; or introduces Himself as superior to other creatures due to comparative attributes such as "the most merciful of the merciful (in Arabic: أَرْحَمُ الرَّاحِمِينَ) (The Holy Quran, Sura al-Mu'minun/ 14, Al-Saffat/125) and “the best of creators” (in Arabic: أَحْسَنُ الْخَالِقِين) (The Holy Quran: Sura al-A'raf/ 151, Yusuf/ 64, Yusuf/92, al-Anbiya/ 83). On the other hand, there are phrases that depict the corporality of God Almighty such as "the hand of Allah is above their hands. (in Arabic: يَدُ اللَّهِ فَوْقَ أَيْدِيهِمْ) The Holy Quran: Sura Fath/10). Also, in contrast to the metaphorical aspect, there are many verses that deny any resemblance of God to other creatures. For example, in Surah al-Shura, verse 11, the Almighty God mentions: "Nothing is like Him" (in Arabic: لَيْسَ كَمِثْلِه شيء) (The Holy Quran: Sura al-Shura / 11). Researchers in rational philosophy and Islamic mysticism believe that the truth speech in this regard is neither a mere purification nor a complete simile, but the truth is the sum of these two terms. In this sense, in theological discussions, God, in His attributes, is both similar to creatures and purified from them, and the perfections that exist in creatures also exist in God. But it should be noted that this does not mean that the perfection of creatures with all the attributes is exactly in God, because the attributes in the creature are associated with a kind of defect and limitation, but in God, the same attribute is without defect and limitation. On the other hand, in the view of Muslim mystics, especially Ibn Arabi, God has neither complete objectivity with creatures nor completely separate from them; Rather, the creatures are the manifestation and expression of the names and attributes of God Almighty. Therefore, Ibn Arabi, based on his own epistemological and ontological principles, while confirming the appearance of the verses that prove the attributes of being corporality to God, never considers the essence of truth to be limited to these attributes and the aspects of imperfection and possibility hidden in it. Rather, he tries to mix the metaphorical attitude in the position of multiplicity of names and attributes with purification in the position of unity of the essence of truth in the form of manifestation states (Saffari Ahmadabad et al 2018, 95-96; Baghdadi 1982, 106-312; Ibn Arabi 2014, 39).

SIMILE AND PURIFICATION IN THE PHILOSOPHY OF DECORATION OF BRICKLAYING IN TAJ AL-MOLK’S DOME

Taj Al-Molk dome, called the earthen dome by ordinary people, is the first dome built by Taj Al-Molk Khosrow Firooz Shirazi in the northernmost part of one of the most important and oldest Islamic buildings in Isfahan named Jāmeh Mosque (also known as the Atiq Mosque and the Friday Mosque). It is one of the most beautiful domes of mosques in the Islamic land with an artistic and ideal position and is a mirror of the magnificent reflection of decorations in the form of brickwork and moulding with geometric, plant and written motifs that reflect the rich history of the Seljuk period (Honarfar 1977, 106).

In Islamic art, The Idea of the Holy is the manifestation of the superior worlds in the psychic domain of existence and its source is the spiritual world. Artist is the one who is able to create art through ascension to the spiritual world on the one hand and knowledge of the sacred world on the other hand. All world phenomena apparently have a truth that refers to the divine names, and artists describe the worlds that mystics express in the form of the manifestation level of the divine names. The most important factor in sacred art is the content of the work and how it is used. In other words, what prevails in the mind of the artist is the inner state and content of the motifs. Islamic art includes various features and aspects of symbols, each of which expresses a specific feature. This approach reproduces the nature of Islamic art in a special role with a semiotic method (Nasr 2001, 512; Schuon 1993, 96; Sadri, 2008: 69; Mahdavi nejad 2002, 26). In fact, philosophy is a kind of worldview that emerges rationally and its goal is to systematize in the field of thought. Iranian-Islamic art is a translation of Iranian-Islamic philosophy that has a close relationship with that worldview and thought, part of which is manifested in the decorations of Iranian Islamic art by the artist But since the visual representation of living beings was forbidden in Islamic law and was considered a danger to idolatry, and due to the relative limitations of other arts such as painting, sculpture, music, and sometimes, even, their prohibition, Iranian artists tended to developed different styles in abstract fields. In addition to functional features, they used various geometric patterns and shapes in their works as a metaphorical and symbolic language of their special and distinct concepts and worldview. The idea of post-Islamic Iranian culture tends to be more abstract due to monotheistic values and mystical tendencies, affects the decorative arts and leads to integration of traditional Iranian-Islamic arts, which signifies common culture as the foundation of this art. One of the common features in these arts is that they are phantom and imaginative, which is associated with cognition, spirituality and morality, so it is a rational, moral, tasteful and decorative art. Therefore, it can be stated that the philosophy of decoration in Iranian-Islamic art is sacred and is a translation of concepts that are basically the language of mysticism for infinite embodiment. It is a combination of both theoretical and practical philosophy. The main issues in theoretical philosophy is question about existence, the discovery of the necessary being, the oneness of the creator of the universe and the knowledge of the divine essence. Practical philosophy shows insight and understanding of those concepts in the form of beautiful art using the element of decoration, gives it a material form and brings that invisible unity and oneness to the stage of manifestation in material forms. The philosophy of decoration is the relation of explanation between form and content. With the preference and superiority of the purified and content attitude over the metaphorical attitude and the material aspect of the work, decorative motifs appear in its form in an abstract and geometric format, in a way that leads the artist to his/her lofty goal, which is the manifestation of the essence of truth and the unity of existence, based on the unity in multiplicity and multiplicity in unity, by coordinating the structure of the components in a single whole, and the artist and his/her superiority emphasize more on the content of the work rather than its material form.

Imagination is the origin of art and artistic beauty, and the world of imagination creates art in the mind of the artist. Because achieving beauty in Iranian-Islamic works of art is an inseparable element of the mind of the Iranian artist, so imagination appears in the form of simile and purification and mainly in a busy state in different dimensions. Thus, these two terms appear in the philosophy of decoration as a fundamental principle in post-Islamic Iranian art. The literal meaning of decoration is adornment, something that adorns and beautifies, all of which emphasize the value of the material. Jones says "Islamic architecture is not the architecture of form, and its themes are designed more in the form of decorations". But decoration in the bricklaying art of the Seljuk period, especially in the Taj Al-Molk building, with a separate meaning from adornment and beauty, shows the meaning of refinement and structural harmony and coordination of components with a single whole. Along with its beauty, it shows a special order and harmony in the art of this dome. "Simile and purification", as a mystical approach, has led to the formation of a special language in the structure of Iranian art, therefore, in the philosophy of decoration, the mystic artist has used it as a tool to design the beauty of God in forms through the embodiment of unity and expressed his/her immediate and intuitive perception of his/her inner journey by using simile and purification in his/her art without relying on concepts in order to beauty and decipher it to be understood by everyone. Since mere imitation of the appearance of nature has no suitable place in Islamic culture, brick laying decorations of this dome are a kind of imitation and inspiration of the geometry and interior of nature, which has been manifested in various forms in this art. It is rooted in ancient beliefs and Islamic thought and is to a large extent the pre-Islamic historical identity of Iran. Artist is a mystic whose unity of existence minimizes his/her distance from his/her Creator. Ala ud-Daula Simnani, a mystic of the seventh and eighth centuries AH, composes in this regard. He writes: "This is not me, if it is me, it is you / if it is a shirt on me, it is you" (Elias 1996, 99).

GEOMETRIC PATTERNS IN IRANIAN ISLAMIC ART

Islamic art is the art derived from the religious truths of Islam, which in terms of form, it can be a continuation of evolved artistic forms throughout the history of Islamic civilization, and according to Burckhardt, this art is basically derived from monotheism (Yasini 2016, 7).

Basically, non-decorative arts have no place in post-Islamic Iranian culture, and the foundation of beauty in our artworks is based on decoration. Decoration is a common philosophy among Iranian Islamic arts that understands the concept of originality of existence and is a tool to convey spiritual messages and semantic beliefs of the artist. It has a sacred nature that is inspired by nature on decorated surfaces and is one of the most fundamental and effective unifying components in Iranian-Islamic art. The designer of decorative motifs in Iranian Islamic art only used plant, geometric and linear motifs. Thus, what appears in the decorative motifs of Iranian Islamic art is a religious and philosophical form that expresses the highest religious concepts and allusions of the spiritual world. Motifs are combined to recreate spiritual concepts in material forms and become more general and unified patterns. In the hierarchy of levels dimensions, patterns are contributed to the joining of each level to another, and everything is limited to what lies ahead (Ardalan and Bakhtiar 2001, 31). To explain the wisdom of using these motifs, it can be stated that the universe was created by a wise Creator, all of whom have a certain order, justice, harmony, proportion and rhythm, and finally they are a kind of multiplicity in unity, which refers to the existence unity of the essence of Supreme Being. Islamic art, in fact, is the limitation of order and the revelation of the laws, that is the crystallization manifested in geometric forms. When this unity in decoration wants to appear symbolically, all points are placed towards a central point or axis, and the principles of geometry, which are evident in all Islamic arts, are linked to cosmic and philosophical concepts. One of its uses is to put together and repeat simple patterns that can be expanded to infinity. Decorative and geometric motifs are used as a unifying mediator between material and the spiritual world to express the artist's ideas. (Ansari, 2002: 70-71).

Case study

The school of Isfahan, which is the culmination of a mixture of Shiite philosophical and mystical thought, was created due to the special attention of Safavid period to art and architecture for the emergence of these ideas in the architecture of this school (Moradi Nasab et al, 2018: 27). One of the most important architectural decorations in the Seljuk period (5th to 6th century AH) is the brickwork of the Taj Al-Molk dome. This dome is unique in terms of brick layouts and uses very beautiful and decorative elements of brickwork.

Due to the multiplicity of decorative forms in this mosque and dome, this study focuses only on the analysis of two patterns with geometric patterns of the dome decorations on the south wing in the southwest corner and the decoration of the north wing design on the northwest corner of the dome. From the author's point of view, it can express significant issues about mysticism and understanding the causes of the presence of simile and purification in the philosophy of Islamic Iranian art decoration, their relationship with each other and the artist's goals. Therefore, the images of the patterns have been photographed by the author. Its designs have been carefully analyzed, studied and represented by the author.

Figure 1.Overview of the dome of Taj Al-Molk Source: Author

ANALYSIS OF THE BRICKLAYING DECORATIONS OF THE SOUTHERN WING DESIGN IN THE SOUTHWEST CORNER OF THE TAJ AL-MOLK DOME

One of the most beautiful decorations of the brick geometric patterns of this building has been engraved in the design of the south wing in the southwest corner of the dome, formed by a skillful combination of carved brick pieces. It expresses a Seljuk artist’s thinking based on his/her inherent attributes such as perfectionism. It shows a kind of idealism and creation of aesthetics of unity and shows that the artist intends to depict the divine light and embodiment of the spiritual world (as a symbol of infinity, divine light and enlightenment, the vastness of the world and the greatness of creation) in his/her mind in this architectural space. These attributes have been represented and manifested in these motifs with the help of simile and purification. In these motifs, he/she depicted three main suns with a full motif consisting of a ten-pointed star and a ten-pointed shamsa in its center and two suns with a half motif on the lower left and right of the image. He also depicted the pentagram white shamsa or stars (which is a metaphor of light and purity) in a state of rotation around them with order, harmony, rhythm and symmetry. It shows the arrangement of the art of unique and omnipotent creator in the material art of mystic artist (Fig. 2). Under the highest sun and in the central part, there is the image of the five stars of a different form from the other star, six motifs combined with each other, exceeds the multiplicity, and creates a larger pentagonal geometric motif in the whole unit together.

Figure 2.Analysis of the bricklaying decorations of the southern wing design in the southwest corner of the Taj Al-Molk dom 

The total number of these motifs is 7 geometric forms, the combination of which with five surrounding stars and the creation of another pentagon shows a geometric form of 7 other motifs. It seems that this expression of unity in multiplicity can refer to the holiness of the number seven in the Holy Quran and the religion of Islam. These motifs can indicate the creation of the world in six stages and its completion in the seventh stage of creation referring to verses 3 of Surah Yunus “Indeed your Lord is Allah, who created the heavens and the earth in six days, and then settled on the Throne, directing the command” (in Arabic: إن رَبَكُمْ الئة الذي خلق السّمَاوَات والأزضن في ستة أيام ثم اسْتوَئ عَلى القزش شيدبتز الأمر) The Qur'an also mentions the purposes of the creation of the sun in verses 5 of Surah Yunus “It is He who made the sun a radiance” (in Arabic: هُوَ الَّذِي جَعَلَ الشَّمْسَ ضِيَاءً), in verse 97 of Surah al-An'am “It is He who made the stars for you” (in Arabic: وَهُوَ الَّذِي جَعَلَ لَكُمُ النُّجُوم), in verse 16 of Surah al-Nahl “and the landmarks [as well]—and by the stars they are guided” (in Arabic: ۚ وَبِالنَّجْمِ هُم يَهْتَدُو نَ وَعَلَامَاتٍ), and in verse 15-19 of Surah Nuh “Have you not seen how Allah has created the seven heavens in layers, and has made therein the moon for a light and the sun for a lamp?...” (in Arabic: أل تَرَؤا كَيْف خَلَقَ الله ستنع ستماؤات طباقا ؛ وجعل الْقَمَرَ فيهن نُورًا وَجَعَلَ الّشن سِرَاجًا) Due to the value of its epistemological concepts, these motifs was placed by unity in the center of the work and the suns were imagined around them in a dependent and circular manner, as if they rotate freely around each other (Fig. 3).

Figure 3.Analysis of pattern, multiplicity in unity and seven geometric forms Source: Author

In some verses of the Holy Quran, God mentions the guiding role of the stars for human beings in the darkness of the sea and land, and according to the abundance of star designs in this design, they can be compared to the guiding star of Muslims. Star motifs can also be a symbol of the Yemani star, which in the wisdoms of some Islamic mystics is a symbol of the whole soul. (Sajjadi 1991, 459; Holy Quran, the seventh sura, verse 96). According to Islamic mystics, shamsa or the sun is also a symbol of the light from divine manifestations, the truth of God's light and the essence of oneness, which also refers to unity, and it is a purification and simile of the rotation of the world wheel, light, divine order and justice, as well as unity in multiplicity as the most prominent position of unveiling of the soul. In this regard, Iranian Muslim artists express the concept of unity in multiplicity and multiplicity in unity using this design in many of their works. In some sources, shamsa is also used as a symbol of prophet. (Sajjadi, 1991: 374; Ansari 1964, 406; Khazaee, 2001: 38). On the other hand, the use of these two motifs in the decoration of this design can be considered as a kind of obedience of the artist to the one Creator of the world, who says: “Indeed We have adorned the lowest heaven with the finery of the stars” (Holy Quran, Sura Al-saffat, Verse 6). That is, where God used the stars to decorate the sky, the Seljuk artist also used a star motif in his/her decorations in accordance with this tradition and the idea of the holy. In other words, the motif of the Iranian star is a symbol of sun cross because shamsa is most similar in appearance to the sun. (Rasekh Talkhdash 2008, 70-71). It should be noted that the sun cross is one of the most ancient Iranian motifs that have been used in the philosophy of Iranian Islamic artists in various forms including the sun and the multi-pointed star after the Islamic period. “The motif of shamsa is a symbol of light resulted from the manifestations of holiness and truth of the light of God and oneness in the eyes of Islamic mystics and Sufis. According to Sufis, since light is the consideration of the manifestation of the Truth and the existence of the Truth in itself, the motifs of shamsa and star can be a simile of this divine light which is considered as the foundation of mysticism and wisdom of the East" (Hosseini, 2011, 11). The geometric motif of shamsa or pentagram star (five-pointed star) in the decoration philosophy of this design refers to "sacred numbers and geometry" in the mind of the Iranian-Islamic artist, which originates from his/her spiritual and religious beliefs and has many meanings. For example, number 5 is usually associated with human life and the five senses.

This number is involved in general astronomical processes. In ancient times, the solar year was divided into 5 periods of 72 days, which later changed into a 365-day year. In the Islamic tradition, in addition to the five pillars of the religion including "Shahada, Salah (prayer), fasting, Zakat, Hajj," Muslims have five daily prayers. Sharia (Islamic law) is divided into 5 categories: mandatory, recommended, neutral, abhorred, and prohibited. During the times of war, booty is divided into 5 categories to pay one-fifth of the acquired wealth (khums). Ahl al-Kisa, or the People of the Cloak, are the family member of Islamic prophet Muhammad; his daughter Fatimah; his cousin and son-in-law Ali; and his two grandsons Hassan and Husayn. They are also called Aal al-Aba (Arabic: ٱلْعَبَاء آل ʾĀl al-ʿAbāʾ ) and in Persian Panj-Tan (Persian: پنج تن), meaning 'the Five'. They were the most important Shiite personalities and highly respected among Sunnis. No set of the mysterious letters (muqaṭṭaʿāt, Arabic: حُرُوف مُقَطَّعَات ḥurūf muqaṭṭaʿāt, "disjoined letters" or "disconnected letters") of the Holy Qur'an is more than five letters (Schimmel, 2009: 127-131). The use of the geometric motif of the shamsa or the ten-pointed star in the decorations of this design has the same characteristic of the sacredness of numbers and geometry. In the book “The Brethren of Purity (Arabic: إخو ن الصفا,) romanized: Ikhwān Al-Ṣafā; also, The Brethren of Sincerity)”, the authorities of the kings has been mentioned ten times, for each of which there are ten characteristics. Khajeh Abdullah Ansari has found ten verses for each of the ten times of behaviour (Bakhtiar 1960, 97-102). As this design has been examined, we have seen that the geometric motif of shamsa has a special place in its decorations and different types including five-pointed and ten-pointed stars have been used extensively. Considering the position of these motifs in this design, it can be inferred that this method of decoration was not chosen randomly by the artist and did not have a purely functional aspect of decoration and beauty, but its usage was rooted in deep doctrinal, mystical, religious and figurative concepts of the idea of the holy, which had been used in the form allegory (the combination of simile and purification) due to the proportion of the motifs of shamsa and star with concepts such as the divinity of the essence of the Almighty, light and sky (they have a special place in Islamic mysticism and the idea of the holy). Since the concepts and the sacred mystical secrets hidden in the numbers, along with the decoration of these geometric motifs, clarify further their practical features in this design, so it can be called "sacred decoration" or "holy decoration". Because, according to Islamic mysticism and the idea of the holy, the whole creation of God designed based on geometry. Therefore, these decorations can be considered as an objective symbol of multiplicity in unity (a metaphorical attitude in the position of multiplicity of attributes such as unity, order, justice, harmony, coordination and balance, etc., with purification in the divinity of the essence of truth and the state of manifestation of the unity of truth in a hierarchical manner). The Iranian artist expresses the principle of connection between the material world and the world of meaning by using these decorative motifs. Art work is nothing but something that expresses this fact. Artist is a mystic who discovers the hijab and a world emerges in his/her mind. Since traditional art is associated with the divine command, the idea of the holy is hidden at the heart of this art, and like religion, it is both truth and presence (Nasr, 2000: 76). The emphasis on his/her monotheistic attitude has expressed by choosing geometric, Islamic, imaginary motifs and the least use of human motifs and the unity of motifs at one point. Emphasis on justice, as one of the foundations of aesthetics in Islamic art and mathematics, was the same as the expression of justice in nature that manifests the exact relations in nature. Therefore, showing the geometric order by using similarity and repetition of the geometric and mathematical patterns, establishing a connection between the whole and part to reach a whole unit, and creating a sense of calm shows the artist's unity creation, unity and infinite manifestation in the decorations (purification of God’s sacred essence). Order, symmetry and proportion, as one of the most important infrastructures of the philosophy of sacred decoration and a unifying factor, are the complements of centralism and emphasizes the axes that balance the space, make the viewer happy, facilitate the understanding of beauty, and creates a static atmosphere. It can be clearly stated that the artist uses the eternal pattern, not the tangible forms, in these themes as if his/her phantasm (imaginal forms) join the apparitional figure of the celestial world and manifests "unity in multiplicity and multiplicity in unity", which is manifested more in harmony in Iranian art (purified from oneness and glorification of the essence of the Most Sacred). According to Islamic mysticism, it is the uniqueness of the existence of God (Bolkhari Qhahi, 2011: 21; Guénon et al., 2007: 147).

ANALYSIS OF THE BRICKLAYING DECORATIONS OF THE NORTHERN WING DESIGN IN THE NORTHWEST CORNER OF THE TAJ AL-MOLK DOME

One of the most beautiful decorations of the geometric brick decorations of this building is engraved in the design of the north wing in the northwest corner of the dome by a Seljuk artist, which has been formed with amazing harmony in the pieces of carved bricks. It shows a spiritual and mystical view. This design reflects a kind of aesthetic unity in this dome with its perfectionist rhythm, balance and proportions, as if represents the embodiment of these elements in the creation of the world wonderfully. The motif used in this design is "cross or crucifix" which is itself has a valuable place in the culture of Iranian and Islamic art and has many concepts hidden behind its motif (Fig. 4).

Figure 4.Analysis of the bricklaying decorations of the northern wing design in the northwest corner of the Taj al-Molk dome 

Cruciform motifs are one of the beautiful motifs used before Islam and the Islamic period. This motif is very simple, concise and abstract and has been used in pre-Islamic times to decorate various arts. These motifs have a special place in the architectural decorations of the Islamic period. The thoughtful artists of the Islamic era realized the importance of symbolism and aesthetics of these motifs from the very beginning and accordingly, by using them, they turned them into one of the main decorative elements of the Islamic period. Cross or crucifix is a gentle word that is in the form of two intersecting and perpendicular lines and in a complete and broken form. In the Islamic period, it is a sign and position of unity and the manifestation of the four main directions and angels overseeing the four seasons. In literature and Mysticism, it is also a manifestation of nature and attributes of the Glory. Cross with four arms and sometimes in combination with blessed names and prayers such as Allah, Muhammad and Ali have been used for decorating the handicrafts of Iranians after Islam. On nights, when the sky is clear, cloudless and dust-free, as we stare at the sky, we see glimmering of stars in the form of a cross or Becrux (Bakhtortash 1977, 69-70). Therefore, it can be acknowledged that the Seljuk artist depicted the idea of illuminating the stars on his/her design and considered it as a metaphor of the supernatural world. This motif consists of two equal-sized line segments that are perpendicular to each other at their center points. These line segments do not emphasize on a specific direction and do not create a feeling of stretching in a specific direction. But most of all, their intersection is intended (Ghaem 2010, 41). In fact, it has a center and four axes (five parts) and four corner spaces are also involved in its formation. Therefore, the numbers that come out of it are 4 (four directions or the same axes of the cross), 5 (four axes of the cross plus the center of the cross) and 9 (center sign, four main axes and four corners) which is called the nine-part pattern of the cross. Finally, the design motifs are taken from numbers that have found their way to the objective domain. In Islamic thought, the four arms of the cross are similes and symbols of: the four pillars of the universe, integrity, universality, earth, order, evolution, size, four seasons, justice, main directions (the peak of this feature is in the four corners of the Kaaba), the existence of the four elements of water, earth, air and fire (all of which are darkness and a person is under these darkness and when he/she appeals to the Truth, he/she can get rid of it) (Bolkhari, 2011: 487), introduction of the four veils in Islam (world, soul, the people and the devil), the light of knowledge will not enter the heart until these four veils are taken from the heart, and whoever removes these four veils, take Taharat or Ghusl (Islamic ritual bath of the whole body from the head to the feet) and is in permanent purity or Taharat (Goharin 1989,166-173).

There are 4 obligatory prostrations in the Qur'an, mentioning the name of the Prophet as the last messenger of God 4 times in the Qur'an, beginning 4 chapters in the Qur'an with the command "Qul" (in Arabic: قُل) means say, and so on. In fact, the artist borrowed the crucifix pattern. He/she has used it to enumerate the divine attributes. It seems that the science of geometry is a powerful tool in the hands of Muslim artists who, by using similes and purification, create proportions, balance and harmony, beauty and order of the Creator's creation in his/her art, which shows the belief in the sanctity of his/her art and the choice of a symbolic language with spiritual characteristics to create his/her work. Geometrically, the cross is the creator of the circle, or sphere, which is the most perfect shape and a symbol of the lightness and general mobility of the soul of the shapes (Ardalan and Bakhtiar, 2001, p. 29). Cross that points to the four corners of the world symbolizes “great peace”, brotherhood and unity among all the people around the world (Rezaei, 2013: 100). It unites all these meanings in its center. The selection of those meanings has appeared in the form of a goal by the Seljuk artist in accordance with the motif of this design. The correlation of the bricklaying motifs of this design with the concepts of simile and purification induces and evokes the intrinsic meanings (oneness), attributes (the Glory, the Beauty and the Great), the Acts of God (justice and balance) and various aspects of monotheism that cause the sanctification of forms of these patterns. Because "it is not possible to reflect the various aspects of monotheism, except through the absurding (impossibility) or transformation of the parts in a whole, multiplicity in unity, and consequently the reference to monotheism."

The central point of the cross also has superior semantic features alone. At this point all contradictions are resolved. This point is equal to the divine position and in the term of Islamic mysticism, this divine position is achieved through the community and unity of opposing elements. This center is the intersection of the greater and the lesser worlds, the point of settlement and compromise, the source of departure and return, and the intersection of the two horizontal and vertical axes (corporal and spiritual, material and spiritual). The movement from the center to the circumference of the circle is the manifestation of the journey in the world of determination and diversity, while the movement towards the center is spiritual and a symbol of absolute unity (Esfandiari 2009). According to Titus Burckhardt, the crucifix implies the concept of the circle- rotation imagination of the sun in its original form. This design is dynamic octagon in geometry created from the center, forming a cross between a square encompassed or engraved in a circle. (Fig. 5).

Figure 5.Analysis of a nine-part cross pattern among a square encompassed or engraved in a circle Source: Author

Ardalan also states that the cross has a nine-part pattern like magic circle. Magic circle is between the action of a circle and a square, and while it begins with unity, it moves through manifestation and returns to unity. It is a cosmic design that is represented in various ways throughout human cultures. In Islam, the concept of magic circle refers to a simile of divine names and attributes. In his description of the Ascension, the Prophet mentions a huge pearl dome that was placed on a square with four columns in the corner, and on these four pillars, four-squared symbol of Quran "In the name of God, the Most Merciful, the Most Compassionate" was written and four streams of blessings flowed from it. The dome was located on a square and its border was octagonal, the symbol of the eight angels, the word of the throne. This Magic circle is a symbol of celestial garden (RozeRezvan) and a transcendental relationship with the Quranic verse 3 of Sura al-Hadid "He is the First and the Last, the Manifest and the Hidden, and He has knowledge of all things" (Ardalan & Bakhtiar, 2001: 31).

In general, one of the most important features of the brickwork decorations of these two patterns is the use of the elements of order, proportion, balance, symmetry, rhythm and harmony, which, in Islamic art, are dimensions that express the invocation of mystical behavior of the artist. It reminds passing from multiplicity to unity and unity to multiplicity. As Ibn Arabi has described it in this way in his book “Alfotohat Al-makiyeh”, “Existence, which is the Reality (God), in the sense that it is itself, is neither whole, nor part, nor general, nor specific, nor unique in unity beyond its essence, nor multiplicity, but according to levels and authorities, these things accompanies it. This existence becomes absolute, constrained, whole, part, general, specific, unique and plural, without any change in its essence and reality” (Ibn Arabi, 1914: 4). The geometric patterns of these patterns also include the concepts and evaluations of positive, negative and symmetrical space which is the consensus of simile and purification of the attributes of God's justice and equality, and none of them has superiority over the other and shows the basis of its monotheistic and purposeful thoughts. The holy light and the divine ray equally shine the whole universe and the creatures. Burckhardt says that "the balance and proportion of the decorations in a building is a reflection of the unity and harmony of the divine life-giving ray on the creatures." (Burckhardt, 1991: 145). The concept of symmetry compared to other decorative elements of Islamic art and architecture has a very prominent place in these two patterns and its function refers to the mirror aesthetics in Islamic architecture and symbolizes eternity and infinity by repeating symmetrical designs and shows a sense of harmony, balance and unity (Papadopoulo, 1989: 62). Mulla Sadra says: "All the entities (essences) are the mirrors of the existence of the Supreme Being and the places of the Self-Discloser manifestation of His holy truth, and the nature of each mirror, because it is a mirror, shows the form which has manifested in it" (Mulla Sadra 2001, 356). According to Nasr, in the sacred architecture of Islam, unity indirectly fills the presence in the architectural spaces and places human as the successor of God directly in the presence of the Glory of Oneness. (Nasr, 1991: 59). It seems that the use of simile and purification in the decorations of this design can be a strong proof of the relative presence between the consensus of the two in the philosophy of decoration in the mind of the Seljuk artist who used and manifested them to achieve his/her goal. It is believed that by using it, the artist turns the divine manifestation into a center of spirituality and value by bringing divine names and attributes in the light of spiritual and sacred dimensions. He/she imagines a material form for God that carries a moral, doctrinal and mystical structure. According to Burckhardt, the origin of the beauty of objects is the attributes of divine beauty and perfection, and Islamic art is essentially a manifestation of general truth. An object is perfect or beautiful to the extent that it reflects one of the divine attributes with the help of simile. " we cannot recognize perfection in anything unless we know how that thing can be the mirror of the manifestation of God (metaphorical attitude)". Mulla Sadra considers the attributes of God the same as His essence and no attribute. There is no existential distinction from another attribute, rather, all, while having a conceptual distinction, have an existential unity. That is, His essence has no existential distinction from attributes. In such a way that each of them is a separate person and also no attribute has an existential distinction from the other attribute, but all of them, while having a conceptual distinction, have existential unity (Mulla Sadra 2001, 145) (Consensus of metaphorical and purified attitude). Ibn Sina's words in the seventh book of “Shafa” also emphasize that "everything possible is composed of being and nature". It can certainty be stated that the Seljuk artist, trying to use the consensus of metaphorical and purified attitude and the relative superiority of purification to simile, has used multiplicity of motifs in the manifestation and emergence of the principle of the Necessary Existence in unity. It indicates the manifestation of divine truth in the form of one of divine names; Its most important theoretical basis is the theory of belief in the fundamentality of existence and ideality of quiddity (Meysamy, 2018: 37 and 38; Mulla Sadra, 1981, 38-45). Therefore, the decorations of these two patterns indicate that the artist was inspired by the Holy Quran and influenced by his/her religion and beliefs. Since the most important spiritual principle in the Qur'an is monotheism, considering the single worldview, he/she has established his/her relationship with his/her art in the purified attitude of the decorative motifs of this dome based on monotheism, gives exoteric form to the philosophy of unity in multiplicity and multiplicity in unity as one of the main foundations of the rich Islamic art culture and combines with his/her art, finds a decorative and purposeful nature, knows that the basis of his/her existence is to move towards the one divine essence and the principle of monotheism, tries to show the divine attributes and truth in the brick by brick of this dome using decipherment and purified attitude and gives the philosophy of decoration an apparent meaning.

CONCLUSIONS

“The idea of the holy” is a celestial origin, and visual art is a form of this origin that is experienced as a symbolic language of the artist's spiritual beliefs in material form. "Simile and purification" is one of the concepts in theology and mysticism. As an approach in theoretical mysticism, these two concepts have led to the formation of a language in Iranian art based on sanctity and monotheism and is inspired by Islamic sources such as monotheism, justice and so on, to which the aesthetics of Islamic art is focused. Since the secret of purification is in the inner name of the Truth and the secret of simile is the properties of the exoteric name of the Truth, so the decline of the Truth from the inner and the forms of the world is not possible. Since this concept is most explicitly expressed in the Qur'an, the Muslim artist imitates the spiritual concepts of Islamic law and the Qur'an to create a work of art. In Ibn Arabi's view, the Qur'an and the Islamic attitude are the result of a consensus of metaphorical and purified concepts; Therefore, it can be concluded that Iranian Islamic art is also a special language of truth that is rooted in the theoretical foundations of his/her wisdom, and in the field of the artist's action, it becomes an expressive expression to represent the two-dimensional world in the appearance of a single light that manifests the truths by divine creation. Simile is the basis of all imaginal forms in art; therefore, the essence of God is manifested in forms by metaphor, trope, and personification. Purification means pure and refined in which all creatures are placed in a longitudinal relation to God and become god-like and purified in the course of evolution to reach the whole God. If the artist is always present and observant in his/her work, he/she tries to use the phenomena of the universe in allegorical and cryptic language in connection with the origin of the universe in order to express the truths of the spiritual world in the hierarchy of existence and divine manifestation. The allegory of this word in the mystical attitude is like a drop to reach the sea and move from the multiplicity of the possible world to the unity of truth. Therefore, his/her art is sacred and the manifestations of its motifs are embodied far from the laws of the material world. According to the metaphorical attitude, his/her insight originates from the beauties of creation and what is superior to him/her becomes the purified attitude and the content of the work, which has linked to the metaphorical attitude in the material world and is manifested in the consensus of the two allegorically. Nasr states that art is the result of opening the eyes of the artist and reaching the status of intuition (Nasr, 2003: 6). The relationship between the discovery and intuition of the artist is revealed and his/her art is transformed into an esoteric interpretation or beloved discovery (transition from outward to inward). In explaining the concepts of simile and purification, unity is manifested in multiplicity, and the infinite forms and images of world returns multiplicity to divine truth. Therefore, art, based on the special epistemological and ontological foundations of the artist, like Ibn Arabi's view, while confirming the appearance of verses that prove the corporal attributes of God, never limited the essence of truth to these attributes and aspects of hidden imperfection and possibility. Rather, he/she tries to combine the metaphorical attitude in the position of the multiplicity of names and attributes with the purification in the position of the unity of the essence of truth, in the form of manifestation in his/her art.

In fact, in the philosophy of decoration, simile and purification is an esoteric approach and manifestation of the spiritual world in Iranian Islamic art, which is manifested in the form of decorative motifs and material domain. They express the true essence and always try to connect the material world to the world of idea. Satisfaction of the inner desire of the artist is based on the discovery and intuition of connecting with the sacred domain of the Divinity. Beautiful geometric appearance in the decorations of Islamic Iranian art motifs are manifested by repeating and merging motifs such as shamsa, stars, etc. apart from material beauty, mystical expression, spirituality and holiness in these pure forms with the help of homogenity, repeating geometric and mathematical patterns, establishment of a connection between the whole and the part in reaching a single whole of "unity in multiplicity and multiplicity in unity", creating a feeling of peace, unity and infinite manifestation of the artist (to represent purified attitude of oneness and purity of the essence of the Most Sacred, that is manifested in Iranian art in harmony and coordination. According to Islamic mysticism, it is the monopoly of the existence of God, which includes all other things in terms of goal and encompassing, and there is nothing beyond His control, and all is in color and a manifestation of God Himself. Because language is incapable of describing Him, the artist uses allegorical language (simile and purification) in the decorative forms of his/her philosophy. This language is the best means of communicating the fundamental truths of the divine essence and is a gateway from the divine presence through which the earthly human enters into his/her inner journey and removes the veil of these material forms to bring the divine light and holy spirituality into his/her existence. He/She faces the greatness and unity of God, and his/her art be a re-creation of the truths that are the abrogation of creation. Therefore, with the studied example, what is proved is that the Iranian Islamic artist is placed as a mediator between the sacred art and the audience, who make the means of developing divine grace in the body of the material world possible by spiritual growth and acquiring moral virtues with the help of simile and purification. By gaining knowledge of the truth and the idea of the holy from the universe, he/she restore the holiness in the course of divine wisdom in his/her art using the philosophy of sacred decoration. Since "decoration" means purification and separation of the individual from his/her individuality and "simile and purification", as a mystical approach, has led to the formation of a special language in the structure of Islamic Iranian art; Therefore, in the philosophy of decoration, the mystic artist has used this philosophy as a tool to manifest the beauty of God in forms through the embodiment of unity and his/her immediate and intuitive perception of his/her inner journey, without relying only on material concepts or aesthetic perception, but, in order to manifest the idea of the holy, he/she pretends with symbolism and irony in simile and purification, and decodes and expresses the most exalted truths of creation and the objective concept of true unity in a mental state, in material, abstract and geometric motifs to be understood by all. In all its aspects, his/her art is based on the monotheism of wisdom and on the grace emitted by the speech of revelation. In fact, in his/her art, the Iranian-Islamic artist combines the two principles of beauty and spirituality with "simile and purification" in the "philosophy of sacred decoration" and manifests the "sacred art".