The golden ratio is an irrational number that approximately equals 1.618. For artistically-minded people, the ratio—or better yet, the divine proportion—might be easier to understand visually. This is easiest to demonstrate with the golden spiral, which is often depicted and constructed within a rectangular frame.
While the result is technically not a truly logarithmic, or “golden,” spiral, it is a close approximation. More importantly, this is the type of process artists have used to visualize and apply the divine proportion to their paintings throughout the centuries. Here are several examples of how the golden ratio can be applied to works from art history.
According to historians, the golden ratio was first studied by ancient Greek mathematicians. While some believe the Grecians did associate the ratio with aesthetics and even applied it to achieve beauty (many argue it was intentionally used in the Parthenon) there is little evidence to support this.
Widespread artistic interest in the ratio (within Western circles) can be justifiably associated with the publication of Divina proportione in 1509. The book, written by mathematician Luca Pacioli and illustrated by Leonardo da Vinci, was widely lauded for its clear writing and stunning illustrations. Many believe these qualities allowed it to reach and occupy artistic circles.