Which Greek sculptor wrote a treatise on proportion called the Canon?

The Greek sculptor who wrote a treatise on proportion called the Canon was Polykleitos.

Polykleitos was a major sculptor of the Classical Greek period, probably active in the 5th century BCE. His Canon, or Kanon, set out a theory of ideal bodily proportion and balance. The original treatise is lost, but ancient writers preserved descriptions of its principles, especially the idea that beauty depended on the measured relationship of parts to one another.

Polykleitos is also associated with the Doryphoros, or Spear-Bearer, a nude male figure often understood as the visual embodiment of the Canon. The original bronze has not survived; Roman marble copies provide the best-known evidence for the work. Its contrapposto stance balances tension and rest, helping make the figure a model of Classical harmony.

The Canon was not simply a list of one rigid measurement. It concerned symmetria, a coherent proportional relationship among the body’s parts. This is why Polykleitos is often distinguished from later sculptors such as Lysippos, whose figures generally had leaner bodies and smaller heads. The Canon influenced both ancient artistic theory and later European ideas about ideal human form.