 Purposiveness and necessity are interrelated and Aristotle analyses the matter in Phys. II.9, introducing the distinction between absolute and conditional necessity. Conditional necessity is always subject to achieving an end. A well-known instance is given by Aristotle in 200a10–15: a saw must necessarily be made of iron to do its work. The material, iron, is necessary but does not lead to the production of a saw. Purpose precedes deliberative actions and imposes necessity upon the materials. As for natural events, Aristotle only says: “necessity in the natural [events] is limited to what is called their matter and their motions” (Phys. II.9, 200a30–32), not to the results, and the question arises whether necessity is absolute or conditional.