We have almost reached the point where praise of rationality is held to mark a man as an old fogey regrettably surviving from a bygone age.

If life is to be fully human it must serve some end which seems, in some sense, outside human life, some end which is impersonal and above mankind, such as God or truth or beauty. Those who best promote life do not have life for their purpose. They aim rather at what seems like a gradual incarnation, a bringing into our human existence of something eternal, something that appears to imagination to live in a heaven remote from strife and failure and the devouring jaws of Time.

Change is scientific; progress is ethical; change is indubitable, whereas progress is a matter of controversy.

But as the work proceeded I was continually reminded of the fable about the elephant and the tortoise. Having constructed an elephant upon which the mathematical world could rest, I found the elephant tottering, and proceeded to construct a tortoise to keep the elephant from falling. But the tortoise was not more secure than the elephant, and after some twenty years of very arduous toil, I came to the conclusion that there was nothing more that I could do in the way of making mathematical knowledge indubitable.

If an opinion contrary to your own makes you angry, that is a sign that you are subconsciously aware of having no good reason for thinking as you do.

All human activity is prompted by desire.

The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.