... gratefulness is an attitude that underlies successful functioning over the life course.

We are grateful to people who occasionally help out, but we elevate them to a higher moral plane when they consistently do so, when we can count on them to show up rain or shine, not just when the boss is looking or free coffee is being served ... Along these lines, we value people who are loyal to their groups, who do not jump ship at the first rough weather.

Appreciation of beauty is a strength that connects someone directly to excellence. Gratitude connects someone directly to goodness.

An aha experienced decades ago by one of us is relevant to this point. Halfway through a grueling clinical internship, CP [Christopher Peterson] complained to his supervisor, “No one [meaning the patients] ever says thank you for anything I try to do.” The response from the experienced psychiatrist stopped CP mid-whine: “If they [the patients] could say thank you, how many of them do you think would be in a psychiatric hospital?

Smith observed that society can function purely on utilitarian grounds or on the basis of gratitude, but he clearly believed that societies of gratitude were more attractive in large part because they provide an important emotional resource for promoting social stability.