Men have physical needs, and they have emotions. While physical needs are unsatisfied, they take first place; but when they are satisfied, emotions unconnected with them become important in deciding whether a man is to be happy or unhappy.

If an opinion contrary to your own makes you angry, that is a sign that you are subsciously aware of having no good reason for thinking as you do. [...] The most savage controversies are those about matters as to which there is no good evidence either way. Persecution is used in theology, not in arithmetic, because in arithmetic there is knowledge, but in theology there is only opinion. So whenever you find yourself getting angry about a difference of opinion, be on your guard; you will probably find, on examination, that your belief is going beyond what the evidence warrants.

Well, there are many religions, but I suppose they all worship the same God.

Dogmatism and skepticism are both, in a sense, absolute philosophies; one is certain of knowing, the other of not knowing. What philosophy should dissipate is certainty, whether of knowledge or ignorance.

No man can be a good teacher unless he has feelings of warm affection toward his pupils and a genuine desire to impart to them what he believes to be of value.

The human race may well become extinct before the end of the century. Speaking as a mathematician, I should say the odds are about three to one against survival.

In considering irregular appearances, there are certain very natural mistakes which must be avoided.