Aristotle's Nicomachean Ethics

Aristotle's Nicomachean Ethics
A. Formal definition of happiness or flourishing (eudaimonia) 
Happiness (or flourishing or living well) is a complete and sufficient good. This implies (a) that it is desired for itself, (b) that it is not desired for the sake of anything else, (c) that it satisfies all desire and has no evil mixed in with it, and (d) that it is stable.
B. Material definition of happiness--what it consists in
We have defined happiness formally as the complete and sufficient good for a human being. But there are many different views of what sorts of life satisfy this formal definition. Aristotle specifically mentions the life of gratification (pleasure, comfort, etc), the life of money-making, the life of (political) action, and the philosophical life, i.e., the life of contemplation or study. He has no patience with the life of money-making or the life of gratification, though he agrees with proponents of the latter that a happy life is pleasant.
There are several ways in which Aristotle approaches the question of what happiness consists in. First, he notes that flourishing for plants and animals consists in their functioning well according to their natures. So one question we should ask is this: What is the proper or peculiar function of a human being? Aristotle thinks it obvious that our proper function consists in reasoning and in acting in accord with reason. This is the heart of the doctrine of virtue, both moral and intellectual. So on this line of reasoning we are led to the conclusion that the possession and exercise of moral and intellectual virtue is the essential element in our living well.
A second approach is to survey the goods which we find ourself desiring, since happiness presumably consists in the attainment of some good or set of goods such that to have them in the right way is to be living well. One division of goods is into (i) external goods (wealth, fame, honor, power, friends), (ii) goods of the body (life,...