Science, by itself cannot, supply us with an ethic.

Adventurous men enjoy shipwrecks, mutinies, earthquakes, conflagrations, and all kinds of unpleasant experiences. They say to themselves, for example, 'So this is what an earthquake is like,' and it gives them pleasure to have their knowledge of the world increased by this new item.

We have in fact, two kinds of morality, side by side: one which we preach, but do not practice, and another which we practice, but seldom preach.

More and more people are becoming unable to accept traditional [religious] beliefs. If they think that, apart from these beliefs, there is no reason for kindly behaviour, the results may be needlessly unfortunate. That is why it is important to show that no supernatural reasons are needed to make [people] kind and to prove that only through kindness can the human race achieve happiness.

When we perceive any object of a familiar kind, much of what appears subjectively to be immediately given is really derived from past experience.

I do not pretend to be able to prove that there is no God. I equally cannot prove that Satan is a fiction. The Christian god may exist; so may the gods of Olympus, or of ancient Egypt, or of Babylon. But no one of these hypotheses is more probable than any other: they lie outside the region of even probable knowledge, and therefore there is no reason to consider any of them.

One of the chief obstacles to intelligence is credulity, and credulity could be enormously diminished by instructions as to the prevalent forms of mendacity.