According to the SEP, this was first tackled by Aristotle in his four-fold theory of causation; he recognises that the theory of causation he had inherited typically distinguished two types of cause: material and efficient and thus he needs to justify his introduction of final cause, which he does:

>In *Physics* II8, by showing that an opponent who claims that material and efficient cause alone suffices to explain natural change fails to account for their *characteristic *regularity*

Since in the world there are many things occurring at once; and sometimes in one way, and at other times in another; the neccessary character can sometimes be difficult to discern; one might speculate this was why astronomy was seen originally as the science par excellance that reveals the hidden order as the stars move to the music of the spheres - in fact we only need look up at the sky to observe this, and see it directly as theatre of permenance, in contrast to the earth where all things are subject to change:  coming to be (*genesis*) and passing away (*phthora*).

Of course, on the cosmological scale the heavens are as subject to change as much as all on earth are; but this is our senses magnified by both the instruments of our practical and theoretical sciences; on the human scale - that which we see directly by our own eyes - this distinction remains: and then one can ask is this regularity, this permanence that we see in the skies - the stars in their courses - is illusionary or real; or more deeply, reflects something real.

In Aristotles language, Hume shows that causality is a form of regularity, whose regularity needs explaining; for Hume this was the minds *habit* of regularising. 

Kant replaces habit by what he calls a transcendental argument: arguing from what is, to what the conditions *must* be to  make this possible.

But given Aristotles thesis that such an explanation of the regularity found in nature is a final cause, it's an intriguing question whether Hume or Kant regarded it as such.