On The Heavens
it exists in actuality-but of not existing last year or in the past.
Now suppose it to be in actuality what it is capable of being. It will
then be true to say now that it does not exist last year. But this
is impossible. No capacity relates to being in the past, but always to
being in the present or future. It is the same with the notion of an
eternity of existence followed later by non-existence. In the later
state the capacity will be present for that which is not there in
actuality. Actualize, then, the capacity. It will be true to say now
that this exists last year or in the past generally.
Considerations also not general like these but proper to the subject
show it to be impossible that what was formerly eternal should later
be destroyed or that what formerly was not should later be eternal.
Whatever is destructible or generated is always alterable. Now
alteration is due to contraries, and the things which compose the
natural body are the very same that destroy it.
THAT the heaven as a whole neither came into being nor admits of
destruction, as some assert, but is one and eternal, with no end or
beginning of its total duration, containing and embracing in itself
the infinity of time, we may convince ourselves not only by the
arguments already set forth but also by a consideration of the views
of those who differ from us in providing for its generation. If our
view is a possible one, and the manner of generation which they assert
is impossible, this fact will have great weight in convincing us of
the immortality and eternity of the world. Hence it is well to
persuade oneself of the truth of the ancient and truly traditional
theories, that there is some immortal and divine thing which possesses
movement, but movement such as has no limit and is rather itself the
limit of all other movement. A limit is a thing which contains; and