Beauty - the adjustment of all parts proportionately so that one cannot add or subtract or change without impairing the harmony of the whole.
Source: From a collection of quotations found on the Internet.
-- Leon Battista Alberti, (Feb 14 1404-1472), Italian architect, philospher, poet; He was the principal initiator of Renaissance art theory; wrote De re aedificatoria, 10 vols 1485 which stimulated interest in Roman architecture.