Nothing is more destructive of individual character than for a man to lose all faith in his own abilities for the prosecution of his work.

What sort of philosophy one chooses depends on what sort of person one is.

The person who doubts there is an external world does not need proof: he needs a cure.

We do not act because we know, but we know because we are called upon to act; the practical reason is the root of all reason.

What sort of philosophy one chooses depends, therefore, on what sort of man one is; for a philosophical system is not a dead piece of furniture that we can reject or accept as we wish; it is rather a thing animated by the soul of the person who holds it.

I am satisfied with, and stand firm as a rock on the belief that all that happens in God's world is for the best, but what is merely germ, what blossom and what fruit I do not know.

Upon the progress of knowledge the whole progress of the human race is immediately dependent: he who retards that, hinders this also.