Nothing of importance is ever achieved without discipline. I feel myself sometimes not wholly in sympathy with some modern educational theorists, because I think that they underestimate the part that discipline plays. But the discipline you have in your life should be one determined by your own desires and your own needs, not put upon you by society or authority.

In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted.

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.

Science, by itself, cannot supply us with an ethic. It can show us how to achieve a given end, and it may show us that some ends cannot be achieved. But among ends that can be achieved our choice must be decided by other than purely scientific considerations. If a man were to say, "I hate the human race, and I think it would be a good thing if it were exterminated," we could say, "Well, my dear sir, let us begin the process with you." But this is hardly argument, and no amount of science could prove such a man mistaken.

The search for something permanent is one of the deepest of the instincts leading men to philosophy.

I used, when I was younger, to take my holidays walking. I would cover 25 miles a day, and when the evening came I had no need of anything to keep me from boredom, since the delight of sitting amply sufficed.

Mathematics takes us into the region of absolute necessity, to which not only the actual word, but every possible word, must conform.