“Nature is everywhere a cause of order.” This claim, together with the evidence that Aristotle marshals to support it, forms a consistent theme throughout his entire corpus. There has been and continues to be considerable disagreement about Aristotle's various arguments – their topics, what they say, if they are valid. But there can be neither doubt nor quarrel that within his philosophy as a whole this claim is central: nature is everywhere a cause of order.

As Mansion argues, nature gives the world not only order, but intelligibility. I shall conclude that Aristotle's claim that nature is everywhere a cause of order constitutes a first principle that informs his physics as a science, and consequently, the particular problems and solutions within physics. Beyond his physics, it also appears at work within his metaphysics. Indeed, it constitutes one of his most important philosophic commitments.

As a first principle, this claim is never proven and so is not derived by or within physics – or any other science. Rather, as I shall argue, the topics, proofs, and arguments of Aristotle's physics and metaphysics presuppose and work in terms of the claim that nature is everywhere a cause of order. Hence, we see this claim at work because we see the physics that assumes it as a first principle.