(Also known as the golden section, golden mean or divine proportion). In mathematics the ratio of 1 to the irrational number (1 + √5)/2, denoted by the Greek letter ϕ and approximately equal to 1.618. 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. Video here.

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