But chance also and spontaneity are reckoned among causes: many
things are said both to be and to come to be as a result of chance and
spontaneity. We must inquire therefore in what manner chance and
spontaneity are present among the causes enumerated, and whether
they are the same or different, and generally what chance and
spontaneity are.

    Some people even question whether they are real or not. They say
that nothing happens by chance, but that everything which we ascribe
to chance or spontaneity has some definite cause, e.g. coming "by
chance" into the market and finding there a man whom one wanted but
did not expect to meet is due to one's wish to go and buy in the
market. Similarly in other cases of chance it is always possible, they
maintain, to find something which is the cause; but not chance, for if
chance were real, it would seem strange indeed, and the question might
be raised, why on earth none of the wise men of old in speaking of the
causes of generation and decay took account of chance; whence it would
seem that they too did not believe that anything is by chance. But
there is a further circumstance that is surprising. Many things both
come to be and are by chance and spontaneity, and although know that
each of them can be ascribed to some cause (as the old argument said
which denied chance), nevertheless they speak of some of these
things as happening by chance and others not. For this reason also
they ought to have at least referred to the matter in some way or
other.

    Certainly the early physicists found no place for chance among the
causes which they recognized-love, strife, mind, fire, or the like.
This is strange, whether they supposed that there is no such thing
as chance or whether they thought there is but omitted to mention
it-and that too when they sometimes used it, as Empedocles does when
he says that the air is not always separated into the highest
region, but "as it may chance". At any rate he says in his cosmogony
that "it happened to run that way at that time, but it often ran
otherwise." He tells us also that most of the parts of animals came to
be by chance.

    There are some too who ascribe this heavenly sphere and all the
worlds to spontaneity. They say that the vortex arose spontaneously,
i.e. the motion that separated and arranged in its present order all
that exists. This statement might well cause surprise. For they are
asserting that chance is not responsible for the existence or
generation of animals and plants, nature or mind or something of the
kind being the cause of them (for it is not any chance thing that
comes from a given seed but an olive from one kind and a man from
another); and yet at the same time they assert that the heavenly
sphere and the divinest of visible things arose spontaneously,
having no such cause as is assigned to animals and plants. Yet if this
is so, it is a fact which deserves to be dwelt upon, and something
might well have been said about it. For besides the other
absurdities of the statement, it is the more absurd that people should
make it when they see nothing coming to be spontaneously in the
heavens, but much happening by chance among the things which as they
say are not due to chance; whereas we should have expected exactly the
opposite.

    Others there are who, indeed, believe that chance is a cause, but
that it is inscrutable to human intelligence, as being a divine
thing and full of mystery.

    Thus we must inquire what chance and spontaneity are, whether they
are the same or different, and how they fit into our division of
causes.