This paper aims at questioning the concept of exercise as it is understood in the mannerist treaties of art in the late Cinquecento. It relies on a thorough investigation on the philosophical sources (such as Aristotelism and Neoplatonism) of these artistic theories. For the mannerists, art is a subjective quality that is granted by practice and custom; drawing practice, for instance, is supposed to help the artist create with ease and facility, improving both his manual dexterity and the accuracy of his judgement. The notion of "judgement of the eye", one of the many qualities exercises may involve, suggests that the artist must learn "to see" in order to be able to adapt general rules to fit specific and difficult situations, as Aristotle's prudent man. Drawing, in particular, is regarded as an opportunity of getting an enriched and refined eye by correcting the flaws of one's works. Grace, defined as "facilita nella difficolta", is said to emerge from this frequent practice, but also implies that the artist should be true to himself and follow his own inclinations. Because art is thought as a sort of virtue and concerns the artist's whole life, drawing practice turns into a practice of the Self, through which the artist models, examines and improves himself.
