Aristotle, Nicomachean Ethics
H. Rackham, Ed.

We may now return to the Good which is the object of our search, and try to find out what exactly it can be. For good appears to be one thing in one pursuit or art and another in another: it is different in medicine from what it is in strategy, and so on with the rest of the arts. What definition of the Good then will hold true in all the arts? Perhaps we may define it as that for the sake of which everything else is done. This applies to something different in each different art—to health in the case of medicine, to victory in that of strategy, to a house in architecture, and to something else in each of the other arts; but in every pursuit or undertaking it describes the end of that pursuit or undertaking, since in all of them it is for the sake of the end that everything else is done. Hence if there be something which is the end of all the things done by human action, this will be the practicable Good—or if there be several such ends, the sum of these will be the Good.