The spiritual place of blue color in the wall painting inscriptions of Islamic architecture of Iran from the second to the eighth century(AH)

Color has been one of the most influential elements in expressing artistic features and ornaments various elements since ancient times. Although, less attention has been paid to the issue of why the choice of blue color is placed as the top color in ornaments of Iranian architecture during the Islamic period. Was its widespread use the only reason, or have other colors and reasons also been important? In order to solve the problem, an attempt was made to choose a medium with the best answer. Therefore, based on the remaining data, wall paintings were chosen as the medium for the research between the 9th and 15th centuries. The aim of this research is to determine the preferred color in the inscription and the reasons for its use with the help of the remaining number of buildings in Iran painted in wall painting style. In this regard, questions are also raised; is there a meaningful significant relationship between content and color in these wall paintings' inscriptions? If a color is preferred, what could be the possible reasons for that? Separation and classification of data in this research is a factor that has been able to use acceptable reasons that rely on evidence instead of descriptive words. The necessity of this research also requires achieving a logical process towards traditionalist thoughts about a type of continuity of color which is referred to as blue in this research. The research method of the current research is correlational and it was tried to distinguish whether the inscriptions are religious or non-religious in terms of subject matter and language. Finally, the reasons for using blue color in Islamic, mystical, literary and pre-Islamic sources were investigated. The results of the research in show that the content of most of the inscriptions was religious. also in all cases; except limited cases that have acceptable reasons, the artist has used blue color in the painting or background to express the spiritual, celestial and divine values of religious inscription. Evidence shows that out of a total of 205 inscriptions on walls, only 5 were done with non-blue colors. Based on this, when examining the color causes of heterogeneous inscriptions, we encountered several important cases. One of these cases is the red inscription of Gonbad-e Soltaniyeh and the other two are Persian inscriptions of Qal'eh Afraasiyab and Togh-e Bolandiyeh House. The use of red color in the inscription of the dome of Soltaniyeh was intended to draw the viewer's attention to the subject of Oljaytu's death. The artist's attention to the issue of language type is also evident in the simultaneous use of different colors in the Afraasiyab Castle (Figure 4), where blue is used in Arabic inscriptions and a different color is used for Persian inscriptions. Arabic was, in fact, the language that God chose to reveal His will in the Quran. This can also be seen in the foundation and burial inscriptions, where only Arabic was used, indicating their suitability for choosing blue as a color. In the following, it is clear that the artist used a variety of colors, including green, yellow, black, and red, in painting of the inscriptions, but only used blue color for painting or the background of the inscription with the content and theme which has been chosen in Quranic and religious. The results in response to the second question indicate that the Quran does not have much agreement with this color, and even with reference to verse 102 of Surah Taha which mentions blue, an opposing interpretation may be possible. From an Islamic mysticism perspective and based on the opinions of Sheikh Alaa al-Dawla Semnani, Kabiri, and Najm al-Razi, blue was among the prominent colors but not at the highest level that could be used as a representation of spiritual elements. Finally, by examining the history of lapis lazuli usage as a valuable material, it becomes clear that it was used in the past as a supplement to gold and was likely used to enhance artistic effects. Models of this combination can be seen in ancient art Mesopotamia, Christianity, and Manichaeism. It seems that the closest culture that has been able to have a comprehensive influence on Islamic art in this item is Manichaeism, especially since Manichaeans used lapis lazuli in the background of all their works. All in all, if this issue is fundamentally related to Manichean, it is not far-fetched, because most of the works left by Followers of Mani were also in the field of painting. The final word is that everything that was obtained from the examination of the characteristics of blue color and the inscriptions painted on the wall is a representation of the master artist's effort to keep the color values alive, which became traditional and continued with the motivation of the embodiment of religious art.