The one thing which seems to me quite impossible is to take into consideration the kind of book one is expected to write; surely one can only write the book that is there to be written.

The young were always theoretical; only the middle-aged could realize the deadliness of principles.

People who prefer to believe the worst of others will breed war and religious persecutions while the world lasts.

For God's sake, let's take the word 'possess' and put a brick round its neck and drown it ... We can't possess one another. We can only give and hazard all we have.

Fantasy works inwards upon its author, blurring the boundary between the visioned and the actual, and associating itself ever moreclosely with the Ego, so that the child who has fantasied himself a murderer ends by becoming a Loeb or a Leopold. The creative Imagination works outwards, steadily increasing the gap between the visioned and the actual, till this becomes the great gulf fixed between art and nature. Few writers of crime-stories become murderers--if any do, it is not the result of identifying themselves with their murderous heroes.

He had the appeal of a very young dog of a very large breed -- a kind of amiable absurdity.

The only ethical principle which has made science possible is that the truth shall be told all the time. If we do not penalize false statements made in error, we open up the way for false statements by intention. And a false statement of fact, made deliberately, is the most serious crime a scientist can commit.