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

The primitive meaning of the two words is the existence
of one thing and the non-existence of another. The third
element which is the connexion between the two words is a
necessary relation to us. The proof is that, if we should
suppose a destruction of the world in the future and
afterwards a second existence for us, we should then say
‘God was without the world’, and this would be true, whether
we meant its original non-existence or the second nonexistence,
its destruction after its existence. And a sign that
this is a subjective relation is that the future can become
past and can be indicated by the word ‘past’.’ All this is the
consequence of the inability of our imagination to imagine
the beginning of a thing without something preceding it, and
this ‘before’ of which the imagination cannot rid itself is
regarded as a really existing thing, namely time. This
resembles the inability of the imagination to admit a limited
body, e.g. overhead, without anything beyond its surface, so
that it is imagined that behind the world there is a space
either occupied or empty; and when it is said there is above
the surface of the world no beyond and no farther extension,
this is beyond the grasp of the imagination. Likewise, when it
is said that there is no real anterior to the existence of the
world, the imagination refuses to believe it. But the
imagination may be called false in allowing above the world
an empty space which is an infinite extension by our saying
to it: empty space cannot be understood by itself, for
extension is the necessary attribute of a body whose sides
comprise space;’ a finite body implies the finiteness of
extension, which is its attribute and the limitation of occupied
space; empty space is unintelligible, therefore there is
neither empty nor occupied space behind the world,
although the imagination cannot admit this. And in the same
way as it is said that spatial extension is an attribute of body,
temporal extension is an attribute of motion, for time is the
extension of movement just as the space between the sides
of a body is the extension of space. And just as the proof
that the sides of a body are finite prevents the admission of a
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