A man's thinking goes on within his consciousness in a seclusion in comparison with which any physical seclusion is an exhibition to public view.

Uttering a word is like striking a note on the keyboard of the imagination.

The world of those who are happy is different from the world of those who are not.

For a large class of cases - though not for all - in which we employ the word meaning it can be explained thus: the meaning of a word is its use in the language.

Suppose someone follows the series "1,3,5,7, ..", and in writing the series 2x+1; and he asked himself "But am I always doing the same thing, or something different every time?" If from one day to the next someone promises: "Tomorrow I will give up smoking", does he say the same thing every day, or every day something different?

It would strike me as ridiculous to want to doubt the existence of Napoleon; but if someone doubted the existence of the earth 150years ago, perhaps I should be more willing to listen, for now he is doubting our whole system of evidence.

Logic takes care of itself; all we have to do is to look and see how it does it.