Do not weep; do not wax indignant. Understand.

The things which ... are esteemed as the greatest good of all ... can be reduced to these three headings, to wit : Riches, Fame, and Pleasure. With these three the mind is so engrossed that it cannot scarcely think of any other good.

Whatever increases, decreases, limits or extends the body's power of action, increases decreases, limits, or extends the mind's power of action. And whatever increases, decreases, limits, or extends the mind's power of action, also increases, decreases, limits, or extends the body's power of action.

Many errors, of a truth, consist merely in the application of the wrong names of things. For if a man says that the lines which are drawn from the centre of the circle to the circumference are not equal, he understands by the circle, at all events for the time, something else than mathematicians understand by it.

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.

Peace is not the absence of war, but a virtue based on strength of character.

Ambition is the immoderate desire for honor.