Canon

( κανὼν, from κάνη, i. e. anything straight like a reed). A fixed rule or standard which is supposed to have served, in antiquity, as a basis or model in forming statues, the various members of which bore a definite proportion one to the other. The Greeks had some such canon. The δορυφόρος (spearman) of Polycletus was, it is said, looked upon as affording a standard for the proportions of the human body. The Egyptians are also supposed to have had a canon, in which the middle finger formed the unit of measurement.