ARISTOTLE AND THE EARLIER PERIPATETICS vol.I by Eduard Zeller, B.F.C.Costelloe 1897

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METAPHYSICS 389
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that, none of the succeeding causes could operate.
This conclusion cannot be avoided by presuming that
the object moved produces its own motion, since it is
necessary for the motive force already to be what the
object moved is to become : ' and hence the same thing
cannot at the same time and in the same relation be
both moved and moving.
admit a primum mobile.
We are forced, therefore, to
That principle, again, might
be either something moved and therefore something
self-moving, or something unmoved. The first of these
cases, however, resolves itself into the second, for
even in a self-impelling substance the motive force
must of necessity be different from what it moves.
Consequently there must be an Unmoved Substance,
which is the cause of all motion. 2 Or—as this is elsewhere
more briefly demonstrated—since all motion
must start from a motive principle, a motion which has
no beginning presupposes a motive principle which is
as eternal as the motion itself, and which, as the presupposition
of all motion, must be itself unmoved. 3
Thus,
then, we obtain three elements : that which merely is
moved and never causes motion, = Matter ; that which
both causes motion and is itself moved, = Nature ;
that
which causes motion without itself being moved, = God. 4
Our previous pages will have shown that this position
1
Cf. p. 381, supra. irivra tpdaprd. oW aBivarov KiVrj-
2
Phys. viii. 5, cf . vii. 1 and aw