The Canon was a theoretical treatise written by Polyclitus that is now completely lost. In it the sculptor set out his system of sculptural composition and defined proportional distribution as the functional correspondence of the parts and members of the human body.
The central subject of the text is the perfect man, understood not only as physical perfection but also as the correspondence between beauty - expressed through symmetry and proportion - and goodness. Harmony, the relation of the parts to the whole, was achieved through numerical relationships based on a Pythagorean interpretation of proportion as divine order.
It is likely that Polyclitus used the Doryphoros as the paradigm of his canon.