The Complete Aristotle (eng.)

to be spontaneous or by
chance. (The distinction between the two must be made later-for the
present it is sufficient if it is plain that both are in the sphere
of things done for the sake of something.)
    Example: A man is engaged in collecting subscriptions for a
feast. He would have gone to such and such a place for the purpose
of getting the money, if he had known. He actually went there for
another purpose and it was only incidentally that he got his money
by going there; and this was not due to the fact that he went there
as a rule or necessarily, nor is the end effected (getting the
money) a cause present in himself-it belongs to the class of things
that are intentional and the result of intelligent deliberation. It
is when these conditions are satisfied that the man is said to have
gone ‘by chance’. If he had gone of deliberate purpose and for the
sake of this-if he always or normally went there when he was
collecting payments-he would not be said to have gone ‘by
chance’.
    It is clear then that chance is an incidental cause in the
sphere of those actions for the sake of something which involve
purpose. Intelligent reflection, then, and chance are in the same
sphere, for purpose implies intelligent reflection.
    It is necessary, no doubt, that the causes of what comes to pass
by chance be indefinite; and that is why chance is supposed to
belong to the class of the indefinite and to be inscrutable to man,
and why it might be thought that, in a way, nothing occurs by
chance. For all these statements are correct, because they are well
grounded. Things do, in a way, occur by chance, for they occur
incidentally and chance is an incidental cause. But strictly it is
not the cause-without qualification-of anything; for instance, a
housebuilder is the cause of a house; incidentally, a fluteplayer
may be so.
    And the causes of the man’s coming and getting the money (when
he did not come for the sake of that) are innumerable. He may have
wished to see somebody or been following somebody or avoiding
somebody, or may have gone to see a spectacle. Thus to say that
chance is a thing contrary to rule is correct. For ‘rule’ applies
to what is always true or true for the most part, whereas chance
belongs to a third type of event. Hence, to conclude, since causes
of this kind are indefinite, chance too is indefinite. (Yet in some
cases one might raise the question whether any incidental fact
might be the cause of the chance occurrence, e.g. of health the
fresh air or the sun’s heat may be the cause, but having had one’s
hair cut cannot; for some incidental causes are more relevant to
the effect than others.)
    Chance or fortune is called ‘good’ when the result is good,
‘evil’ when it is evil. The terms ‘good fortune’ and ‘ill fortune’
are used when either result is of considerable magnitude. Thus one
who comes within an ace of some great evil or great good is said to
be fortunate or unfortunate. The mind affirms the essence of the
attribute, ignoring the hair’s breadth of difference. Further, it
is with reason that good fortune is regarded as unstable; for
chance is unstable, as none of the things which result from it can
be invariable or normal.
    Both are then, as I have said, incidental causes-both chance and
spontaneity-in the sphere of things which are capable of coming to
pass not necessarily, nor normally, and with reference to such of
these as might come to pass for the sake of something.
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6
    They differ in that ‘spontaneity’ is the wider term. Every
result of chance is from what is spontaneous, but not everything
that is from what is spontaneous is from chance.
    Chance and what results from chance are appropriate to agents
that are capable of good fortune and of moral action generally.
Therefore necessarily chance is in the sphere of moral actions.
This is indicated by the fact that good fortune is thought to be
the same, or nearly the same, as happiness, and happiness to be a
kind of moral action, since it is well-doing. Hence what is not
capable of moral action cannot do anything by chance. Thus an
inanimate thing or a lower animal or a child cannot do anything by
chance, because it is incapable of deliberate intention; nor can
‘good fortune’ or ‘ill fortune’ be ascribed to them, except
metaphorically, as Protarchus, for example, said that the stones of
which altars are made are fortunate because they are held in
honour, while