Benjamin Franklin "I will speak ill of no man"

B.F.Skinner, the world-famous psychologist, proved through his experiments that an animal rewarded for good behavior will learn much more rapidly and retain what it learns far more effectively than an animal punished for bad behavior. Later studies have shown that the same applies to humans. By Criticizing, we do not make lasting changes and often incur resentment.

Hans Selye, another great psychologist, said, "As much as we thirst for approval, we dread condemnation."

Criticism is futile because it puts a person on the defensive and usually makes him strive to justify himself. Criticism is dangerous, because it wounds a person's precious pride, hurts his sense of importance, and arouses resentment.

(... Abraham Lincoln put the letter aside, for he had learned by bitter experience that sharp criticisms and rebukes almost invariably end in futility.)

Benjamin Franklin, tactless in his youth, became so diplomatic, so adroit at handling people, that he was made American Ambassador to France. The secret of his success? "I will speak ill of no man," he said, "... and speak all the good I know of everybody."
-- Excerpt from "How to Win Friends & Influence People"
Written by Dale Carnegie