They who are to be judges must also be performers.

The body is most fully developed from thirty to thirty-five years of age, the mind at about forty-nine.

God and nature create nothing that does not fulfill a purpose

We must be neither cowardly nor rash but courageous.

All men naturally desire knowledge. An indication of this is our esteem for the senses; for apart from their use we esteem them for their own sake, and most of all the sense of sight. Not only with a view to action, but even when no action is contemplated, we prefer sight, generally speaking, to all the other senses. The reason of this is that of all the senses sight best helps us to know things, and reveals many distinctions.

No science ever defends its first principles.

In part, art completes what nature cannot elaborate; and in part it imitates nature.