Americans say they are happiest when they earn around US$75,000 a year, according to a poll by a team of Princeton University researchers of 450,000 Americans last year. The researchers found that exorbitant amounts of money do not necessarily translate into happiness, because people grow bored of even the most expensive toys. The excitement of buying a multi-million-dollar house does not last forever. After a couple of months, it just becomes the place where you hang your coat.

Instead, people who make around $75,000 a year and spend a lot of leisure time with their family and friends tend to be the happiest.

The U.S. psychologist Ed Diener said the reason that Koreans always come bottom in international happiness surveys is their "excessive materialism." Diener researched people from 130 countries and found that Koreans are more influenced by material values even than Americans or Japanese. But happiness comes from forming deep relationships with others, being challenged to learn new things, having a strong sense of meaning in life, setting clear goals and being thankful for everyday things.

But Koreans, Diener found, tend to consider money the absolute precondition for happiness. At this rate, Koreans will end up feeling less and less happy even as their country becomes more affluent.

A piece that defines the middle class in Korea has gone viral on social networking sites. The defining characteristics are having no debt, living in an apartment more than 100 sq.m, earning more than W5 million a month, driving a mid-sized sedan, having at least W100 million in the bank and being able to afford overseas travel once a year (US$1=W1,104).

Perhaps Koreans place so much importance on money because they are learning that it is increasingly difficult to enjoy such a lifestyle today. In one survey in August, 50 percent of Koreans said they are not in the middle class but in the low-income bracket. This shows how many people feel they are missing out.

The online piece about the middle class also touches on the standards for measuring quality of life proposed by French president Georges Pompidou in the early 1970s. They included learning more than one foreign language and how to play an instrument, enjoying sports and being able to raise one's children to become self-sufficient after graduating from high school. There is a saying that people who are ignorant of foreign languages are ignorant of their mother tongue, while playing a musical instrument allows people to escape from the daily grind and focus on themselves.

Human needs are classified according to different levels in psychology, with physical needs the most basic. Korean society has long passed that stage and is heading toward the needs for safety, esteem and self-fulfillment. But Koreans still try to measure our happiness by how much money they have. Happiness cannot be measured by material riches. It can only come from spiritual wealth.

By Chosun Ilbo columnist Park Hae-hyun