Tahafut_al-Tahafut-transl-Engl-van-den-Bergh

I say:
impossible, for if it were ever impossible, it would not be true
that the existence of the world is eternally possible; and if it
were not true that the existence of the world is eternally
possible, it would not be true that its possibility never
ceases; and if it were not true that its possibility never
ceases, it would be true that its possibility had begun; and if
it were true that its possibility had begun, its existence before
this beginning would not be possible and that would lead to
the assumption of a time when the world was not possible
and God had no power over it.
He who concedes that the world before its existence was of a neverceasing
possibility must admit that the world is eternal, for the assumption
that what is eternally possible is eternally existent implies no absurdity.
What can possibly exist eternally must necessarily exist eternally, for what
can receive eternity cannot become corruptible, except if it were possible
that the corruptible could become eternal. Therefore Aristotle has said that
the possibility in the eternal beings is necessary.’
Ghazali says:
The objection is that it is said that the temporal becoming
of the world never ceased to be possible, and certainly there
is no time at which its becoming could not be imagined. But
although it could be at any time, it did not become at any
time whatever, for reality does not conform to possibility, but
differs from it. You yourself hold, for instance, in the matter
of place, that the world could be bigger than it is or that the
creation of an infinite series of bodies above the world is
possible, and that there is no limit to the possibilities of
increase in the size of the world, but still the actual existence
of absolutely infinite occupied space and of any infinite and
limitless being is impossible. What is said to be possible is
an actual body of a limited surface, but the exact size of this
body, whether it is larger or smaller, is not specified. In the
same way, what is possible is the coming into existence of
the world in time, but the exact time of its coming into
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