All exact science is dominated by the idea of approximation.

A world full of happiness is not beyond human power to create; the obstacles imposed by inanimate nature are not insuperable. The real obstacles lie in the heart of man, and the cure for these is a firm hope, informed and fortified by thought.

The most essential characteristic of scientific technique is that it proceeds from experiment, not from tradition.

Formality Thus the absence of all mention of particular things or properties in logic or pure mathematics is a necessary result of the fact that this study is, as we say, "purely formal".

Brief and powerless is man's life; on him and all his race the slow, sure doom falls pitiless and dark.

A drop of water is not immortal; it can be resolved into oxygen and hydrogen. If, therefore, a drop of water were to maintain that it had a quality of aqueousness which would survive its dissolution we should be inclined to be skeptical. In like manner we know that the brain is not immortal.

Most of the greatest evils that man has inflicted upon man have come through people feeling quite certain about something which, in fact, was false.