Nicomachean Ethics (1.1.1-1.1.5)

(It is true that a certain variety is to be observed among the ends at which the arts and sciences aim: in some cases the activity of practising the art is itself the end,[*] whereas in others the end is some product over and above the mere exercise of the art; and in the arts whose ends are certain things beside the practice of the arts themselves, these products are essentially superior in value to the activities.)

But as there are numerous pursuits and arts and sciences, it follows that their ends are correspondingly numerous: for instance, the end of the science of medicine is health, that of the art of shipbuilding a vessel, that of strategy victory, that of domestic economy wealth.

Now in cases where several such pursuits are subordinate to some single faculty—as bridle-making and the other trades concerned with horses’ harness are subordinate to horsemanship, and this and every other military pursuit to the science of strategy, and similarly other arts to different arts again—in all these cases, I say, the ends of the master arts are things more to be desired than the ends of the arts subordinate to them; since the latter ends are only pursued for the sake of the former.

(And it makes no difference whether the ends of the pursuits are the activities themselves or some other thing beside these, as in the case of the sciences mentioned.)