Nature without learning is blind, learning apart from nature is fractional, and practice in the absence of both is aimless.

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."

For the mind does not require filling like a bottle, but rather, like wood, it only requires kindling to create in it an impulse to think independently and an ardent desire for the truth.

The same intelligence is required to marshal an army in battle and to order a good dinner. The first must be as formidable as possible, the second as pleasant as possible, to the participants.

The usual disease of princes, grasping covetousness, had made them suspicious and quarrelsome neighbors.

A few vices are sufficient to darken many virtues.

Nor is drunkenness censured for anything so much as its intemperate and endless talk.