On The Heavens   

been shown that they are coincident. But when terms stand to one

another as these do, F and H coincident, E and F never predicated of

the same thing but one or other of everything, and G and H likewise,

then E and G must needs be coincident. For suppose that E is not

coincident with G, then F will be, since either E or F is

predictable of everything. But of that of which F is predicated H will

be predicable also. H will then be coincident with G, but this we

saw to be impossible. And the same argument shows that G is coincident

with E.

Now the relation of the ungenerated (E) to the generated (F) is

the same as that of the indestructible (G) to the destructible (H). To

say then that there is no reason why anything should not be

generated and yet indestructible or ungenerated and yet destroyed,

to imagine that in the one case generation and in the other case

destruction occurs once for all, is to destroy part of the data. For

(1) everything is capable of acting or being acted upon, of being or

not being, either for an infinite, or for a definitely limited space

of time; and the infinite time is only a possible alternative

because it is after a fashion defined, as a length of time which

cannot be exceeded. But infinity in one direction is neither

infinite or finite. (2) Further, why, after always existing, was the

thing destroyed, why, after an infinity of not being, was it

generated, at one moment rather than another? If every moment is alike

and the moments are infinite in number, it is clear that a generated

or destructible thing existed for an infinite time. It has therefore

for an infinite time the capacity of not being (since the capacity

of being and the capacity of not being will be present together), if

destructible, in the time before destruction, if generated, in the

time after generation. If then we assume the two capacities to be

actualized, opposites will be present together. (3) Further, this

second capacity will be present like the first at every moment, so

that the thing will have for an infinite time the capacity both of