Do not feel certain of anything.

It has become a commonplace that aggressiveness also often has its roots in fear. I am inclined to think that this theory has been pushed too far. [...] The type of aggressiveness that is the outcome of timidity is not, I think, that which inspires great leaders; the great leaders, I should say, have an exceptional self-confidence which is not only on the surface, but penetrates deep into the subconscious.

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

Memory demands an image.

Philosophy is that part of science which at present people chose to have opinions about, but which they have no knowledge about. Therefore every advance in knowledge robs philosophy of some problems which formerly it had ...and will belong to science.

The fact that a belief has a good moral effect upon a man is no evidence whatsoever in favor of its truth. I'm not contending in a dogmatic way that there is not a God. What I'm contending is that we don't know that there is. I don't like the word "absolute." I don't think there is anything absolute whatever. The moral law, for example, is always changing. At one period in the development of the human race, almost everybody thought cannibalism was a duty.

There is no reason to suppose that the world had a beginning at all. The idea that things must have a beginning is really due to the poverty of our thoughts.