The mathematical and geometrical rules conditioning the relationship of the parts to each other and to the whole.
Since the days of the Ancient Egyptian civilization, artists have employed some system of proportional canon. The Greek canon was established with the famous statue of Doryphorus by POLYCLITUS of SAMOS (5th century BC), and was modified by LYSIPPUS (fl. c.360-316 BC).
Further modifications were introduced by: the Roman VITRUVIUS (fl.46-30 BC), the medieval mason VILLARD de HONNECOURT (fl. 1225-1235 AD), Italian architect and theorist LEON BATTISTA ALBERTI (1404-1472), LEONARDO DA VINCI (1452-1519) and ALBRECHT DüRER (1471-1528), each reflecting particular aesthetic aims.