By extension, the norms of a certain epoch as to what is or is not considered beautiful may be called a canon of beauty. These norms have varied over time and what is considered beautiful in one era may not necessarily be so in another. Canons of beauty follow the evolution of fashion and are dependent on the evolution of physical decoration techniques such as hairdressing or make up.
Under France's Ancien Régime, canons of beauty required a woman to have as white a skin as possible. This was achieved (sometimes to the danger of health) by rouge and face powders as well as 'mouches', fake moles made of black muslin glued onto the face or chest. Today, by contrast, such canons prefer a 'healthier' skin colour, sportiness, gait and so on.
Proportions in art
For his painting The Birth of Venus Sandro Botticelli stated that the distance between the nipple and navel, between the two legs and between the navel and the groin must all be equal for a figure to (in his opinion) be ideally proportioned. Other such systems of 'ideal proportions' in painting and sculpture include the Polyclitean canon and Vitruvian modules, best known in the Vitruvian Man.