Life is not an easy matter... You cannot live through it without falling into frustration and cynicism unless you have before you a great idea which raises you above personal misery, above weakness, above all kinds of perfidy and baseness.

The historic ascent of humanity, taken as a whole, may be summarized as a succession of victories of consciousness over blind forces - in nature, in society, in man himself.

The depth and strength of a human character are defined by its moral reserves. People reveal themselves completely only when they are thrown out of the customary conditions of their life, for only then do they have to fall back on their reserves.

There are no absolute rules of conduct, either in peace or war. Everything depends on circumstances.

Learning carries within itself certain dangers because out of necessity one has to learn from one's enemies.