I am not myself in any degree ashamed of having changed my opinions.

To be happy in this world, especially when youth is past, it is necessary to feel oneself not merely an isolated individual whose day will soon be over, but part of the stream of life flowing on from the first germ to the remote and unknown future.

Dogmatism is the greatest of mental obstacles to human happiness.

A smile happens in a flash, but its memory can last a lifetime.

No opinion has ever been too errant to become a creed.

If the ordinary wage-earner worked four hours a day, there would be enough for everybody, and no unemployment — assuming a certain very moderate amount of sensible organization. This idea shocks the well-to-do, because they are convinced that the poor would not know how to use so much leisure.

The most essential characteristic of scientific technique is that it proceeds from experiment, not from tradition. The experimental habit of mind is a difficult one for most people to maintain; indeed, the science of one generation has already become the tradition of the next