From the concluding chapter to C. S. Lewis’s Studies in Words (2nd ed, Cambridge University Press, 1990):
Adverse criticism, far from being the easiest, is one of the hardest things in the world to do well. . . .
Reviews filled with venom have often been condemned socially for their bad manners, or ethically for their spite. I am not prepared to defend them from either charge; but I prefer to stress their inutility. . . . Automatically, without thinking about it one’s mind discounts everything [the venomous critic] says, as it does when we are listening to a drunk or delirious man. The critic rivets our attention on himself. When we get to the end we find that the critic has told us everything about himself and nothing about the book. Thus in criticism, as in vocabulary, hatred over-reaches itself. Willingness to wound, too intense and naked, becomes impotent to do the desired mischief.
Of course, if we are to be critics, we must condemn as well as praise; we must sometimes condemn totally and severely. But we must obviously be very careful. . . . I think we must get it firmly fixed in our minds that the very occasions on which we should most like to write a slashing review are precisely those on which we had much better hold our tongues. The very desire is a danger signal. . . . The strength of our dislike is itself a probable symptom that all is not well within; that some raw place in our psychology has been touched, or else that some personal or partisan motive is secretly at work. . . . If we do speak, we shall almost certainly make fools of ourselves. Continence in this matter is no doubt painful. But, after all, you can always write your slashing review now and drop it into the wastepaper basket a day or so later. A few re-readings in cold blood will often make this quite easy.