On The Heavens   

also reasonable, since everything ceases to move when it comes to

its proper place, but the body whose path is the circle has one and

the same place for starting-point and goal.



10



Having established these distinctions, we may now proceed to the

question whether the heaven is ungenerated or generated,

indestructible or destructible. Let us start with a review of the

theories of other thinkers; for the proofs of a theory are

difficulties for the contrary theory. Besides, those who have first

heard the pleas of our adversaries will be more likely to credit the

assertions which we are going to make. We shall be less open to the

charge of procuring judgement by default. To give a satisfactory

decision as to the truth it is necessary to be rather an arbitrator

than a party to the dispute.

That the world was generated all are agreed, but, generation over,

some say that it is eternal, others say that it is destructible like

any other natural formation. Others again, with Empedliocles of

Acragas and Heraclitus of Ephesus, believe that there is alternation

in the destructive process, which takes now this direction, now

that, and continues without end.

Now to assert that it was generated and yet is eternal is to

assert the impossible; for we cannot reasonably attribute to

anything any characteristics but those which observation detects in

many or all instances. But in this case the facts point the other way:

generated things are seen always to be destroyed. Further, a thing

whose present state had no beginning and which could not have been

other than it was at any previous moment throughout its entire

duration, cannot possibly be changed. For there will have to be some

cause of change, and if this had been present earlier it would have

made possible another condition of that to which any other condition