Whereas happiness is the highest good, being a realization and perfect practice of virtue, which some can attain, while others have little or none of it, the various qualities of men are clearly the reason why there are various kinds of states and many forms of government; for different men seek after happiness in different ways and by different means, and so make for themselves different modes of life and forms of government.

Suppose, then, that all men were sick or deranged, save one or two of them who were healthy and of right mind. It would then be the latter two who would be thought to be sick and deranged and the former not!

Learning is not child's play; we cannot learn without pain.

Intuition is the source of scientific knowledge.

To write well, express yourself like the common people, but think like a wise man.

But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.

Happiness is a state of activity.