In mathematics the golden ratio, also known as the golden section, golden mean, or divine proportion, is the ratio of 1 to the irrational number (1 + √5)/2 (approximately equal to 1.618, often denoted by the Greek letter ϕ). Some artists (including Salvador Dalí) and architects (including Le Corbusier) have incorporated the golden ratio into their works on the theory that this is the most aesthetically pleasing proportion. Web resource here.

Salvador Dalí. The Sacrament of the Last Supper. Oil on canvas. 1955. National Gallery of Art, Washington, D.C.