Every science and every inquiry tends, it seems, toward some good. That is why men have rightly declared that the good is that at which all things aim. But there appears to be a certain difference among ends: some are activities, others are works distinct from the activities themselves. Where the ends are activities, the activities themselves are the ends; and where there are works, these are superior to the activities. Since the ends are numerous, and some are chosen for the sake of others, there must necessarily be, among the things we choose for themselves, a principle, that is, that which is chosen for the sake of one thing alone, and consequently the good and the sovereign good. Would not this be what all men seek under the name of happiness? For men who lead different lives assign it to different objects: the vulgar life places it in pleasure, which is why it loves a life of mere sensation; remarkable and active men place it in honor, which is yet too superficial to be what we seek, since honor seems to depend on those who confer it rather than on those who receive it; but men seek honor in order to be assured of their own worth, that is, to convince themselves of their own excellence. Three lives, then, present themselves: the life of enjoyment, the political life, the contemplative life. Let us consider the question of the good under another aspect: what would be the good proper to man? For although the goods of each being are different, there is for each something that is its own. If, then, we grant that man acts, lives, and makes choices in accordance with reason, and that man is a being of such a nature, the good of man will be the activity of his soul in accordance with reason, or not contradicted by reason, within a complete life. And further, as we have said, it is in a whole life that this activity must be realized, for one swallow does not make a spring, nor does one day; and in the same way neither a single day nor a short time makes a man happy and blessed. We posit, therefore, that happiness is an activity of the soul in accordance with virtue, and that if there are many virtues, it is in accordance with the best and most perfect of them. As for virtue itself, we must say how it comes to be. Virtue, indeed, is not a science only; it is also a disposition that is formed by acts. We become just by performing just actions, temperate by performing temperate acts, courageous by performing courageous acts. It is by the acts themselves that arise the dispositions which determine activity. Hence from youth onward each must be led to do what is fitting, beginning with pleasures and pains; one must, as Plato says, be trained from childhood to love what ought to be loved and to hate what ought to be hated. Here, then, is how virtue may be defined: it is a disposition to act excellently. But excellence means here choosing what accords with right reason, as reason prescribes. Virtue is a disposition concerned with our actions, consisting in a mean relative to us, this mean being determined by the rule of reason, that is, such as the prudent and wise man would determine it. Virtue has two vices facing it: one by excess, the other by deficiency. Vice assails the mean in the same way that excess and deficiency destroy the health and strength of the body. The habits of excess and deficiency are contrary to one another, but the mean is contrary to both. Such is the law of all opposites. This is why it is difficult to be virtuous, for virtue is a mean; to find the mean is as difficult as to find the center of a circle. Nor is it easy to define the manner, the moment, the persons, the object, and the way that are fitting for anger or for action. Hence we praise those who achieve something in these matters, not completely, but somewhat. Hence also the mean is the way of merit, praised by all. The virtuous man, in fact, behaves as nature itself does, which everywhere places what is perfect in the middle. And no one feels disgust at the mean: all men celebrate it. It is therefore the mean that virtue seeks: the good is what conforms to the mean. But supreme happiness does not reside only in the practice of the moral virtues. The contemplative life is the highest, the one that brings us closest to the gods. If men judge the gods happy and place their happiness in thought and contemplation, it is clear that the life most like theirs is the one that conforms to thought. The contemplative activity is the most continuous, the most self-sufficient, the most loved for its own sake. For it arises from the highest virtue, wisdom, and from the most divine of all objects. If, then, man, like other beings, is the most excellent of beings, happiness will be what is most excellent in him, namely the activity that raises him above all the rest.