Aristotle, Nicomachean Ethics
H. Rackham, Ed.

We can descry an objection that may be raised against our arguments on the ground that the theory in question was not intended to apply to every sort of good, and that only things pursued and accepted for their own sake are pronounced good as belonging to a single species, while things productive or preservative of these in any way, or preventive of their opposites, are said to be good as a means to these, and in a different sense.