one thing were older or younger
than another, it could not become older or younger in a greater degree
than it was at first; for equals added to unequals, whether to periods
of time or to anything else, leave the difference between them the same
as at first.

Of course.

Then that which is, cannot become older or younger than that which
is, since the difference of age is always the same; the one is and has
become older and the other younger; but they are no longer becoming so.

True.

And the one which is does not therefore become either older or younger
than the others which are.

No.

But consider whether they may not become older and younger in another
way.

In what way?

Just as the one was proven to be older than the others and the others
than the one.

And what of that?

If the one is older than the others, has come into being a longer time
than the others.

Yes.

But consider again; if we add equal time to a greater and a less time,
will the greater differ from the less time by an equal or by a smaller
portion than before?

By a smaller portion.

Then the difference between the age of the one and the age of the others
will not be afterwards so great as at first, but if an equal time be
added to both of them they will differ less and less in age?

Yes.

And that which differs in age from some other less than formerly, from
being older will become younger in relation to that other than which it
was older?

Yes, younger.

And if the one becomes younger the others aforesaid will become older
than they were before, in relation to the one.

Certainly.

Then that which had become younger becomes older relatively to that
which previously had become and was older; it never really is older, but
is always becoming, for the one is always growing on the side of youth
and the other on the side of age. And in like manner the older is always
in process of becoming younger than the younger; for as they are always
going in opposite directions they become in ways the opposite to one
another, the younger older than the older, and the older younger than
the younger. They cannot, however, have become; for if they had already
become they would be and not merely become. But that is impossible; for
they are always becoming both older and younger than one another: the
one becomes younger than the others because it was seen to be older and
prior, and the others become older than the one because they came int