The Complete Aristotle (eng.)

the most part musical,
but since this sometimes happens, it must be accidental (if not,
everything will be of necessity). The matter, therefore, which is
capable of being otherwise than as it usually is, must be the cause
of the accidental. And we must take as our starting-point the
question whether there is nothing that is neither always nor for
the most part. Surely this is impossible. There is, then, besides
these something which is fortuitous and accidental. But while the
usual exists, can nothing be said to be always, or are there
eternal things? This must be considered later,’ but that there is
no science of the accidental is obvious; for all science is either
of that which is always or of that which is for the most part. (For
how else is one to learn or to teach another? The thing must be
determined as occurring either always or for the most part, e.g.
that honey-water is useful for a patient in a fever is true for the
most part.) But that which is contrary to the usual law science
will be unable to state, i.e. when the thing does not happen,
e.g.’on the day of new moon’; for even that which happens on the
day of new moon happens then either always or for the most part;
but the accidental is contrary to such laws. We have stated, then,
what the accidental is, and from what cause it arises, and that
there is no science which deals with it.
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3
    That there are principles and causes which are generable and
destructible without ever being in course of being generated or
destroyed, is obvious. For otherwise all things will be of
necessity, since that which is being generated or destroyed must
have a cause which is not accidentally its cause. Will A exist or
not? It will if B happens; and if not, not. And B will exist if C
happens. And thus if time is constantly subtracted from a limited
extent of time, one will obviously come to the present. This man,
then, will die by violence, if he goes out; and he will do this if
he gets thirsty; and he will get thirsty if something else happens;
and thus we shall come to that which is now present, or to some
past event. For instance, he will go out if he gets thirsty; and he
will get thirsty if he is eating pungent food; and this is either
the case or not; so that he will of necessity die, or of necessity
not die. And similarly if one jumps over to past events, the same
account will hold good; for this-I mean the past condition-is
already present in something. Everything, therefore, that will be,
will be of necessity; e.g. it is necessary that he who lives shall
one day die; for already some condition has come into existence,
e.g. the presence of contraries in the same body. But whether he is
to die by disease or by violence is not yet determined, but depends
on the happening of something else. Clearly then the process goes
back to a certain starting-point, but this no longer points to
something further. This then will be the starting-point for the
fortuitous, and will have nothing else as cause of its coming to
be. But to what sort of starting-point and what sort of cause we
thus refer the fortuitous-whether to matter or to the purpose or to
the motive power, must be carefully considered.
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4
    Let us dismiss accidental being; for we have sufficiently
determined its nature. But since that which is in the sense of
being true, or is not in the sense of being false, depends on
combination and separation, and truth and falsity together depend
on the allocation of a pair of contradictory judgements (for the
true judgement affirms where the subject and predicate really are
combined, and denies where they are separated, while the false
judgement has the opposite of this allocation; it is another
question, how it happens that we think things together or apart; by
‘together’ and ‘apart’ I mean thinking them so that there is no
succession in the thoughts but they become a unity); for falsity
and truth are not in things-it is not as if the good were true, and
the bad were in itself false-but in thought; while with regard to
simple concepts and ‘whats’ falsity and truth do not exist even in
thought—this being so, we must consider later what has to be
discussed with regard to that which is or is not in this sense. But
since the combination and the separation are in thought and not in
the things, and that which is in this sense is a different sort of
‘being’ from the things