A History of Greek Philosophy / ARISTOTLE

Page 20

And in the macrocosm, the visible and invisible world about us, the same conception holds: “The existence of God is an eternally perfect entelechy, a life everlasting. In that, therefore, which belongs to the divine there must be an eternally perfect movement. Therefore the heavens, which are as it were the body of the Divine, are in form a sphere, of necessity ever in circular motion. Why then is not this true of every portion of the universe? Because there must of necessity be a point of rest of the circling body at the centre. Yet the circling body cannot rest either as a whole or as regards any part of it, otherwise its motion could not be eternal, which by nature it is. Now that which is a violation of nature cannot be eternal, but the violation is posterior to that which is in accordance with nature, and thus the unnatural is a kind of displacement or degeneracy from the natural, taking the form of a coming into being.

“Necessity then requires earth, as the element standing still at the centre. Now if there must be earth, there must be fire. For if one of two opposites is natural or necessary, the other must be necessary too, each, in fact, implying the necessity of the other. For the two have the same substantial basis, only the positive form is naturally prior to the negative; for instance, warm is prior to cold. And in the same way motionlessness and heaviness are predicated in virtue of the absence of motion and lightness, i.e. the latter are essentially prior.

“Further, if there are fire and earth, there must also be the elements which lie between these, each having an antithetic relation to each. From this it follows that there must be a process of coming into being, because none of these elements can be eternal, but each affects, and is affected by each, and they are mutually destructive. Now it is not to be argued that anything which can be moved can be eternal, except in the case of that which by its own nature has eternal motion. And if coming into being must be predicated of these, then other forms of change can also be predicated” (Arist. De Coelo, ii. p. 3).

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A History of Greek Philosophy : Table of Contents
Cf. D'Arcy W. Thompson, Aristotle's Natural Science

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