Not to know of what things one should demand demonstration, and of what one should not, argues want of education.

Whereas young people become accomplished in geometry and mathematics, and wise within these limits, prudent young people do not seem to be found. The reason is that prudence is concerned with particulars as well as universals, and particulars become known from experience, but a young person lacks experience, since some length of time is needed to produce it.

It is Homer who has chiefly taught other poets the art of telling lies skillfully.

He is his own best friend and takes delight in privacy whereas the man of no virtue or ability is his own worst enemy and is afraid of solitude.

A life of wealth and many belongings is only a means to happiness. Honor, power, and success cannot be happiness because they depend on the whims of others, and happiness should be self-contained, complete in itself.

All men by nature desire to know. An indication of this is the delight we take in our senses; for even apart from their usefulness they are loved for themselves...

The duty of rhetoric is to deal with such matters as we deliberate upon without arts or systems to guide us, in the hearing of persons who cannot take in at a glance a complicated argument or follow a long chain of reasoning.