Physics is mathematical not because we know so much about the physical world, but because we know so little; it is only its mathematical properties that we can discover.

Whatever we know without inference is mental.

I conclude that, while it is true that science cannot decide questions of value, that is because they cannot be intellectually decided at all, and lie outside the realm of truth and falsehood. Whatever knowledge is attainable, must be attained by scientific methods; and what science cannot discover, mankind cannot know.

The doctrine (of) maintaining that the language of daily life, with words used in their ordinary meanings, suffices for philosophy . . . I find myself totally unable to accept . . . . Because it makes almost inevitable the perpetuation amongst philosophers of the muddle-headedness they have taken over from common sense.

If one lived for ever the joys of life would inevitably in the end lose their savour. As it is, they remain perennially fresh.

One must expect a war between U.S.A. and U.S.S.R. which will begin with the total destruction of London. I think the war will last 30 years, and leave a world without civilised people, from which everything will have to build afresh - a process taking (say) 500 years.

Really high-minded people are indifferent to happiness, especially other people's.