Physics   

there cannot be a source of the infinite or limitless, for that would
be a limit of it. Further, as it is a beginning, it is both
uncreatable and indestructible. For there must be a point at which
what has come to be reaches completion, and also a termination of all
passing away. That is why, as we say, there is no principle of this,
but it is this which is held to be the principle of other things, and
to encompass all and to steer all, as those assert who do not
recognize, alongside the infinite, other causes, such as Mind or
Friendship. Further they identify it with the Divine, for it is
'deathless and imperishable' as Anaximander says, with the majority of
the physicists.
Belief in the existence of the infinite comes mainly from five
considerations:
(1) From the nature of time-for it is infinite.
(2) From the division of magnitudes-for the mathematicians also use
the notion of the infinite.
(3) If coming to be and passing away do not give out, it is only
because that from which things come to be is infinite.
(4) Because the limited always finds its limit in something, so that
there must be no limit, if everything is always limited by something
different from itself.
(5) Most of all, a reason which is peculiarly appropriate and presents
the difficulty that is felt by everybody-not only number but also
mathematical magnitudes and what is outside the heaven are supposed to
be infinite because they never give out in our thought.
The last fact (that what is outside is infinite) leads people to
suppose that body also is infinite, and that there is an infinite
number of worlds. Why should there be body in one part of the void
rather than in another? Grant only that mass is anywhere and it
follows that it must be everywhere. Also, if void and place are
infinite, there must be infinite body too, for in the case of eternal
things what may be must be. But the problem of the infinite is
difficult: many contradictions result whether we suppose it to exist
or not to exist. If it exists, we have still to ask how it exists; as
a substance or as the essential attribute of some entity? Or in
neither way, yet none the less is there something which is infinite or
some things which are infinitely many?
The problem, however, which specially belongs to the physicist is to
investigate whether there is a sensible magnitude which is infinite.
We must begin by distinguishing the various senses in which the term
'infinite' is used.
(1) What is incapable of being gone through, because it is not in its
nature to be gone through (the sense in which the voice is
'invisible').
(2) What admits of being gone through, the process however having no
termination, or what scarcely admits of being gone through.
(3) What naturally admits of being gone through, but is not actually
gone through or does not actually reach an end.
Further, everything that is infinite may be so in respect of addition
or division or both.
Part 5
Now it is impossible that the infinite should be a thing which is
itself infinite, separable from sensible objects. If the infinite is
neither a magnitude nor an aggregate, but is itself a substance and
not an attribute, it will be indivisible; for the divisible must be
either a magnitude or an aggregate. But if indivisible, then not
infinite, except in the sense (1) in which the voice is 'invisible'.
But this is not the sense in which it is used by those who say that
the infinite exists, nor that in which we are investigating it, namely
as (2) 'that which cannot be gone through'. But if the infinite exists
as an attribute, it would not be, qua infinite an element in
substances, any more than the invisible would be an element of speech,
though the voice is invisible.
Further, how can the infinite be itself any thing, unless both number