Nothing is harder to direct than a man in prosperity; nothing more easily managed that one is adversity.

Hesiod might as well have kept his breath to cool his pottage.

We ought to give our friend pain if it will benefit him, but not to the extent of breaking off our friendship; but just as we make use of some biting medicine that will save and preserve the life of the patient. And so the friend, like a musician, in bringing about an improvement to what is good and expedient, sometimes slackens the chords, sometimes tightens them, and is often pleasant, but always useful.

Knavery is the best defense against a knave.

This excerpt is presented as reproduced by Copernicus in the preface to De Revolutionibus: "Some think that the earth remains at rest. But Philolaus the Pythagorean believes that, like the sun and moon, it revolves around the fire in an oblique circle. Heraclides of Pontus and Ecphantus the Pythagorean make the earth move, not in a progressive motion, but like a wheel in rotation from west to east around its own center."

It is a hard matter, my fellow citizens, to argue with the belly, since it has no ears.

Children are to be won to follow liberal studies by exhortations and rational motives, and on no account to be forced thereto by whipping.