One of the defining characteristics of Islamic art is its abundant use of geometric patterns to adorn a wide variety of architectural and decorative surfaces. The sources of the basic shapes and patterns used in Islamic ornamentation are rooted in the artistic traditions of the pre-Islamic Byzantine and Sasanian empires. During the early spread of Islam in the seventh and eighth centuries, artists encountered a range of patterns and designs that they adopted, abstracting and adapting them into new forms and to support new uses. Although there is little historical evidence that tells us how they worked, we know that Islamic craftsmen continued to elaborate upon these forms through the centuries, ultimately creating new abstract geometric patterns that were symmetrical, proportional, and balanced. These designs were often based on the replication and repetition of a single unit in a sequence of steps to develop the overall pattern. The works of art discussed in this unit are drawn from many regions and span the thirteenth to the seventeenth century. In spite of regional variations, the areas in which the works were produced are united by a common appreciation and taste for geometric patterns.
Islamic geometric design is unique in its elevation to a primary art form—while the earlier traditions upon which Islamic art drew also utilized geometric forms, they were often relegated to the borders or were secondary to a figural composition (fig. 15). Early Islamic artists often privileged the geometric over the figural, covering whole surfaces in dense geometric designs. The reason for this change in focus is not entirely clear. It may have been due in part to the new religious community's desire to distinguish itself visually from previous empires, and in part a need to respond to Islam's avoidance of figural forms in religious or public art. Scholars have suggested other explanations for this tendency, such as an intense cultural focus on textiles in Islamic lands, where covering surfaces with geometric and other types of ornament was akin to draping them in patterned textiles. It is likely that a combination of these factors led to the continuous popularity of calligraphic, geometric, and vegetal (plantlike) ornament in the Islamic world.
The contributions of Islamic mathematicians and other scientists were essential to the development of this unique form of ornament, and their ideas and advanced technological knowledge are reflected in the mathematical exactitude of Islamic geometric patterns. Recent research has shown that mathematicians and artisans met on a regular basis, accounting for the transmission of mathematical concepts from theory to artistic practice. This phenomenon also provides insight into the significant relationship between medium and the technology of patternmaking; the shape and medium of an object informs how the pattern will be translated from mathematical concept into artistic reality. The prevalence of geometric ornament in Islamic art thus shows the confluence of art, mathematics, philosophy, and religious thought.
The basic instruments for constructing geometric designs are a compass and a ruler, tools that generate the circle and line, upon which all such design is based. Using these two simple forms, an artist could create endless variations of patterns and motifs by repeating a single geometric unit laid out according to a basic organizing principle. The result is an overall geometric pattern that is both mathematically rooted and visually harmonious. The circle and line are also the basis for the proportional system used in Islamic calligraphy (see fig. 12). For this reason, scholars often refer to the art of calligraphy as the "geometry of the line."
Complicated patterns are constructed from basic shapes: circles and polygons. The complex patterns found in Islamic art often include many of these shapes in a variety of spatial arrangements.