The truth of a theory is in your mind, not in your eyes.

The one who walks alone, is likely to find himself in places no one has ever been.

The only reason for time is so that everything doesn't happen at once.

Most teachers waste their time by asking question which are intended to discover what a pupil does not know whereas the true art of questioning has for its purpose to discover what pupils knows or is capable of knowing.

Nothing causes more consternation in a group of hypocrits than one honest man.

[O]nly if every individual strives for truth can humanity attain a happier future; the atavisms in each of us that stand in the way of a friendlier destiny can only thus be rendered ineffective.

The world is in greater peril from those who tolerate or encourage evil than from those who actually commit it.