Psychologists have tended to look down their nose at gratitude as little more than a question of having good manners and remembering to say thank you,” McAdams says. Gratitude isn’t even listed in the 1999 addition of the Encyclopaedia of Human Emotions, a standard psychology text. “But if a sense of thankfulness can turn someone’s life from bitter to positive, that makes gratitude an important aspect of psychology,” McAdams notes.

If modern researchers are coming late to the topic of gratitude, philosophers did not. Cicero, born about a century before Jesus, viewed thankfulness to society and to the universe as a virtuous emotion that would counter hubris and allow a person to develop high ethical standards: “Gratitude is not only the greatest of virtues, but the parent of all others,” he said. By the 18th century, Adam Smith, in his Theory of Moral Sentiments, supposed that people who did not feel gratitude were only cheating themselves out of happiness. And in the 19th century, Immanuel Kant described ingratitude with “the essence of vileness.”

Abraham Maslow, who in the 1960s developed the theory of self-actualisation, which holds that human beings satisfy their needs in stages, beginning with physical and gradually rising to “transpersonal” or spiritual needs, despaired of the lack of gratitude in society.

People’s lives were getting better, Maslow wrote, and yet most seemed to be taking their blessings for granted. — Beliefnet.com