golden section

Definition

Division of a line into two unequal parts in such a way that the smaller part ('a') has the same ratio to the larger part ('b') as the larger part has to the whole line (a : b = b: (a + b)). Segment created by this ratio (21:34 or 1:1.618) was called 'the section' by the ancient Greeks (who used it in proportioning the Pantheon and other structures) and termed 'golden' by the Renaissance-era artists who (because of its visually satisfying symmetry) thought it to be divinely proportioned. See also Fibonacci series.