All happiness or unhappiness solely depends upon the quality of the object to which we are attached by love.

The idea, which constitutes the actual being of the human mind, is not simple, but compounded of a great number of ideas.

He who hates anyone will endeavor to do him an injury, unless he fears that a greater injury will thereby accrue to himself; on the other hand, he who loves anyone will, by the same law, seek to benefit him.

Academies that are founded at public expense are instituted not so much to cultivate men's natural abilities as to restrain them.

No one doubts but that we imagine time from the very fact that we imagine other bodies to be moved slower or faster or equally fast. We are accustomed to determine duration by the aid of some measure of motion.

I should attempt to treat human vice and folly geometrically... the passions of hatred, anger, envy, and so on, considered in themselves, follow from the necessity and efficacy of nature... I shall, therefore, treat the nature and strength of the emotion in exactly the same manner, as though I were concerned with lines, planes, and solids.

A man is as much affected pleasurably or painfully by the image of a thing past or future as by the image of a thing present.