The canon is sculpture's proportional grammar — from Polykleitos's lost treatise to the Beaux-Arts academy's rules for the ideal figure.
In sculpture, the codified system of ideal proportion governing the human figure, most famously formulated by Polykleitos in his treatise the Kanon (c. 450–440 BC) and embodied in his statue the Doryphoros; by extension, any authoritative proportional system, including Vitruvius’s architectural canon and later academic systems of bodily and facial measure.
Etymology
From Greek kanōn ("measuring rod, rule, standard"), via Latin canon. The Greek root is likely of Semitic origin (compare Hebrew qāneh, "reed"), but entered sculptural and architectural vocabulary through Greek technical writing, then through Vitruvius's Latin, and thence into Italian canone, French canon, and English "canon."
Sculptor Notes
Polykleitos of Argos wrote a treatise called the Kanōn, now lost, in which he set out a system of commensurable ratios relating the parts of the body to one another and to the whole; his bronze Doryphoros ("Spear-Bearer," c. 450–440 BC, known today through Roman marble copies) is generally understood to be the practical demonstration of that written rule. Ancient sources describe later sculptors following Polykleitos's Canon "like a law," which is precisely the point: a canon is not a static formula for a single pose but a modular grammar — a base unit (often the length of a finger joint) multiplied and combined to generate the proportions of hand, foot, head, and total figure, so that any part properly measured yields the others. This is the origin of the module-based thinking sculptors still use when scaling maquettes, and it operates in tandem with the shifting weight and axial counterbalance we now call contrapposto.
Vitruvius extends the same logic from the body to the building in Book III of De Architectura, arguing that a well-formed temple must exhibit the same symmetria found in a well-proportioned man, and providing his own set of ratios for intercolumniation, column height, and capital proportion. This passage is the direct ancestor of Leonardo's Vitruvian Man, and it is why the sculptor's canon and the architect's canon cannot be fully separated in a tradition — like the one this glossary serves — where cathedral sculpture and cathedral fabric were designed by overlapping guild knowledge.
The medieval workshop tradition preserved its own working canon distinct from the classical one, most visibly in the convention of dividing the face into thirds (hairline to brow, brow to base of nose, base of nose to chin), a system carried through Gothic portal sculpture and still taught in figure-drawing and portrait-carving instruction today. The nineteenth-century École des Beaux-Arts synthesized these strands — classical antique casts, Vitruvian ratios, and empirical life study — into its own academic canon. A stone carver should understand the canon not as a cage but as a checked reference: a way of catching proportional error before it is fixed irreversibly in marble.