He who does not understand that a dead lion is more alive than a living dog will remain a dog.

Every man should view himself as equally balanced: half good and half evil. Likewise, he should see the entire world as half good and half evil.... With a single good deed he will tip the scales for himself, and for the entire world, to the side of good.

Further, there are things of which the mind understands one part, but remains ignorant of the other; and when man is able to comprehend certain things, it does not follow that he must be able to comprehend everything.

Consequently he who wishes to attain to human perfection, must therefore first study Logic, next the various branches of Mathematics in their proper order, then Physics, and lastly Metaphysics.

When I have a difficult subject before me - when I find the road narrow, and can see no other way of teaching a well established truth except by pleasing one intelligent man and displeasing ten thousand fools - I prefer to address myself to the one man, and to take no notice whatever of the condemnation of the multitude; I prefer to extricate that intelligent man from his embarrassment and show him the cause of his perplexity, so that he may attain perfection and be at peace.

In the beginning we must simplify the subject, thus unavoidably falsifying it, and later we must sophisticate away the falsely simple beginning.

Every man whose character traits all lie in the mean is called a wise man.