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.

One swallow does not make a spring, nor does one fine day.

The man with a host of friends who slaps on the back everybody he meets is regarded as the friend of nobody.

Youth should stay away from all evil, especially things that produce wickedness and ill-will.

The physician himself, if sick, actually calls in another physician, knowing that he cannot reason correctly if required to judge his own condition while suffering.

The more you know, the more you know you don't know.

In making a speech one must study three points: first, the means of producing persuasion; second, the language; third the proper arrangement of the various parts of the speech.