 Aristotle analyses substance in terms of form and matter. The form is what kind of thing the object is, and the matter is what it is made of. The term ‘matter’ as used by Aristotle is not the name for a particular kind of stuff, nor for some ultimate constituents of bodies, such as atoms (Aristotle rejects atomism). ‘Matter’ is rather the name for whatever, for a given kind of object, meets a certain role or function, namely that of being that from which the object is constituted. Relative to the human body, matter is flesh and blood. The matter of an axehead is the iron from which it is made. Relative to the elements, earth, fire, air, and water, matter is an intrinsically characterless ‘prime matter’ that underlies the qualities of them all.