Aristotle, Nicomachean Ethics
H. Rackham, Ed.

activity （since the intellect is the highest thing in us, and the objects with which the intellect deals are the highest things that can be known） , and also it is the most continuous, for we can reflect more continuously than we can carry on any form of action. [3] And again we suppose that happiness must contain an element of pleasure; now activity in accordance with wisdom is admittedly the most pleasant of the activities in accordance with virtue: at all events it is held that philosophy or the pursuit of wisdom contains pleasures of marvellous purity and permanence, and it is reasonable to suppose that the enjoyment of knowledge is a still pleasanter occupation than the pursuit of it. [4] Also the activity of contemplation will be found to possess in the highest degree the quality that is termed self-sufficiency; for while it is true that the wise man equally with the just man and the rest requires the necessaries of life, yet, these being adequately supplied, whereas the just man needs other persons towards whom or with whose aid he may act justly, and so likewise do the temperate man and the brave man and the others, the wise man on the contrary can also contemplate by himself, and the more so the wiser he is; no doubt he will study better with the aid of fellow-workers, but still he is the most self-sufficient of men.