The Complete Aristotle (eng.)

and call them good-tempered,
but sometimes we praise those who get angry and call them manly.
The man, however, who deviates little from goodness is not blamed,
whether he do so in the direction of the more or of the less, but
only the man who deviates more widely; for he does not fail to be
noticed. But up to what point and to what extent a man must deviate
before he becomes blameworthy it is not easy to determine by
reasoning, any more than anything else that is perceived by the
senses; such things depend on particular facts, and the decision
rests with perception. So much, then, is plain, that the
intermediate state is in all things to be praised, but that we must
incline sometimes towards the excess, sometimes towards the
deficiency; for so shall we most easily hit the mean and what is
right.

Nicomachean Ethics, Book III
    Translated by W. D. Ross
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1
    Since virtue is concerned with passions and actions, and on
voluntary passions and actions praise and blame are bestowed, on
those that are involuntary pardon, and sometimes also pity, to
distinguish the voluntary and the involuntary is presumably
necessary for those who are studying the nature of virtue, and
useful also for legislators with a view to the assigning both of
honours and of punishments. Those things, then, are
thought-involuntary, which take place under compulsion or owing to
ignorance; and that is compulsory of which the moving principle is
outside, being a principle in which nothing is contributed by the
person who is acting or is feeling the passion, e.g. if he were to
be carried somewhere by a wind, or by men who had him in their
power.
    But with regard to the things that are done from fear of greater
evils or for some noble object (e.g. if a tyrant were to order one
to do something base, having one’s parents and children in his
power, and if one did the action they were to be saved, but
otherwise would be put to death), it may be debated whether such
actions are involuntary or voluntary. Something of the sort happens
also with regard to the throwing of goods overboard in a storm; for
in the abstract no one throws goods away voluntarily, but on
condition of its securing the safety of himself and his crew any
sensible man does so. Such actions, then, are mixed, but are more
like voluntary actions; for they are worthy of choice at the time
when they are done, and the end of an action is relative to the
occasion. Both the terms, then, ‘voluntary’ and ‘involuntary’, must
be used with reference to the moment of action. Now the man acts
voluntarily; for the principle that moves the instrumental parts of
the body in such actions is in him, and the things of which the
moving principle is in a man himself are in his power to do or not
to do. Such actions, therefore, are voluntary, but in the abstract
perhaps involuntary; for no one would choose any such act in
itself.
    For such actions men are sometimes even praised, when they
endure something base or painful in return for great and noble
objects gained; in the opposite case they are blamed, since to
endure the greatest indignities for no noble end or for a trifling
end is the mark of an inferior person. On some actions praise
indeed is not bestowed, but pardon is, when one does what he ought
not under pressure which overstrains human nature and which no one
could withstand. But some acts, perhaps, we cannot be forced to do,
but ought rather to face death after the most fearful sufferings;
for the things that ‘forced’ Euripides Alcmaeon to slay his mother
seem absurd. It is difficult sometimes to determine what should be
chosen at what cost, and what should be endured in return for what
gain, and yet more difficult to abide by our decisions; for as a
rule what is expected is painful, and what we are forced to do is
base, whence praise and blame are bestowed on those who have been
compelled or have not.
    What sort of acts, then, should be called compulsory? We answer
that without qualification actions are so when the cause is in the
external circumstances and the agent contributes nothing. But the
things that in themselves are involuntary, but now and in return
for these gains are worthy of choice, and whose moving principle is
in the agent, are in themselves involuntary, but now and in return
for these gains voluntary. They are more like voluntary acts; for
actions are in the class of particulars, and the particular acts
here are voluntary. What sort of things