Excerpts from How to Win Friends and Influence People by Dale Carnegie (1940) pp. 34-39.

If some people are so hungry for a feeling of importance that they actually go insane to get it, imagine what miracles you and I can achieve by giving people honest appreciation this side of insanity. Why did Andrew Carnegie pay Schwab a million dollars a year or more than three thousand dollars a day? Why? Because Schwab is a genius? No. Because he knew more about the manufacture of steel than other people? Nonsense. Charles Schwab told me himself that he had many men working for him who knew more about he manufacture of steel than he did. Schwab says that he was paid this salary largely because of his ability to deal with people. I asked him how he did it. Here is his secret set down in his own words--words that ought to be cast in bronze and hung in every home and school, every shop and office in the land--words that children ought to memorize instead of wasting their time memorizing the conjugation of Latin verbs or the amount of the annual rainfall in Brazil--words that will all but transform your life and mine if we will only live them: "I consider my ability to arouse enthusiasm among the men," said Schwab, "the greatest asset I possess, and the way to develop the best that is in a man is by appreciation and encouragement. "There is nothing else that so kills the ambitions of a man as criticisms from his superiors. I never criticize anyone. I believe in giving a man incentive to work. So I am anxious to praise but loath to find fault. If I like anything, I am hearty in my approbation and lavish in my praise." That is what Schwab does. But what does the average man do? The exact opposite. If he doesn't like a thing, he raises the Old Harry; if he does like it, he says nothing. "In my wide association in life, meeting with many and great men in various parts of the world," Schwab declared, "I have yet to find the man, however great or exalted his station, who did not do better work and put forth greater effort under a spirit of approval than he would ever do under a spirit of criticism." I once succumbed to the fad of fasting and went for six days and nights without eating. It wasn't difficult. I was less hungry at the end of the sixth day that I was at the end of the second. Yet I know, and you know, people who would think they had committed a crime if they let their families or employees go for six days without food; but they will let them go for six days, and six weeks, and sometimes sixty years without giving them the hearty appreciation that they crave almost as much as they crave food. When Alfred Lunt played the stellar role in Reunion in Vienna, he said, "There is nothing I need so much as nourishment for my self-esteem." We nourish the bodies of our children and friends and employees; but how seldom do we nourish their self-esteem. We provide them with roast beef and potatoes to build energy; but we neglect to give them kind words of appreciation that would sing in their memories for years like the music of the morning stars. Of course, flattery seldom works with discerning people. It is shallow, selfish and insincere. It ought to fail and it usually does. True, some people are so hungry, so thirsty, for appreciation that they will swallow anything, just as a starving man will eat grass and fish worms. The difference between appreciation and flattery? That is simple. One is sincere and the other is insincere. One comes from the heart out; the other from the teeth out. One is unselfish; the other is selfish. One is universally admired; the other is universally condemned. When we are not engaged in thinking about some definite problem, we usually spend about 95 per cent of our time thinking about ourselves. Now, if we stop thinking about ourselves for awhile and begin to think of the other man's good points, we won't have to resort to flattery so cheap and false that it can be spotted almost before it is out of the mouth. Let's cease thinking of our accomplishments, our wants. Let's try to figure out the man's good points. Then forget flattery. Give honest, sincere appreciation. Be "hearty in your approbation and lavish in your praise," and people will cherish your words and treasure them and repeat them over a lifetime--repeat them years after you have forgotten them.

[If you are not familiar with this book, it was one of the earliest books on improving human relations written for the layperson. Though it was written many years ago, and was initially written for business people, the principles it teaches are as timely as ever and apply to all human relations: spouse, child, friend, parent, co-worker, etc.]