Man knows himself only insofar as he knows the world, becoming aware of it if only within himself, and of himself self only within it. Each new subject, well observed, opens up within us a new organ of thought.

Is it life, I ask, is it even prudence, To bore thyself and bore the students?

Hypotheses are only the pieces of scaffolding which are erected round a building during the course of construction, and which are taken away as soon as the edifice is completed.

Whatever liberates our spirit, without also giving us mastery over ourselves, is destructive.

To become aware in time when young of the advantages of age; to maintain the advantages of youth in old age: both are pure fortune.

Sameness leaves us in peace but it is contradiction that makes us productive.

The decline in literature indicates a decline in the nation. The two keep pace in their downward tendency.