Aristotle, Nicomachean Ethics
H. Rackham, Ed.

[6] Acts of this kind, then, are ‘mixed’ or composite¹; but they approximate rather to the voluntary class. For at the actual time when they are done they are chosen or willed; and the end or motive of an act varies with the occasion, so that the terms ‘voluntary’ and ‘involuntary’ should be used with reference to the time of action; now the actual deed in the cases in question is done voluntarily, for the origin of the movement of the parts of the body instrumental to the act lies in the agent; and when the origin of an action is in oneself, it is in one's own power to do it or not. Such acts therefore are voluntary, though perhaps involuntary apart from circumstances—for no one would choose to do any such action in and for itself.