Why are secular liberals so unhappy? This question is provocatively discussed in Arthur Brooks' new book Gross National Happiness. Brooks is a sociologist and statistician at Syracuse University. I am reading his book while vacationing with my lovely wife on the beautiful island of Santorini. So it's natural for me, watching the most beautiful sunsets in the world, martini in hand, to think about the question of happiness.

Brooks' book is full of interesting data. We learn, for instance, that money does buy happiness, but only upto a point. Poor people and poor countries are unhappy, and by the self-description of the people involved. So the movement from grinding poverty to the comfortable middle-class brings a huge gain in happiness. But interestingly economic improvement at this point brings diminishing marginal returns. This is not to say that rich people aren't happier: they are. But not by very much.

Brooks also shows that, in his own words, "people who say they are conservative or very conservative are nearly twice as likely to say they are very happy than are people who call themselves liberal or very liberal. Conservatives are much less likely to say they are dissatisfied with themselves, that they are inclined to feel like a failure, or to be pessimistic about their future." Conservatives' mental health is far better than that of liberals.

Equally fascinating, Brooks notes that "faith is an incredible predictor, and cause, of happiness. Religious people of all faiths are much, much happier on average than secularists." Specifically, 43 percent of those who attend church weekly or more call themselves "very happy," versus 23 percent who attend seldom or never. Observant Jews and Christians are by Brooks' measure the happiest people in America.

So why are secular liberals in general so miserable? I offer two reasons. The first is that liberals are political utopians. They consider human nature to be wonderful, and they expect freedom to be used wonderfully well. So they are always bitterly disappointed when they discover that this is not the case. Conservatives, by contrast, have a dimmer view of human nature. So their expectations are more modest. When things don't turn out half-badly, conservatives are pleasantly surprised. They are happier because it takes less to make them happier.

It's not too hard to figure out why religious people are happier. Belief in God gives people a powerful sense of higher purpose in life. It assures people that the universe is in the benign hands of a omnipotent, omniscient, and compassionate higher power. It offers people a code for how to live. It gives us a reason to hope in cosmic justice, which is better than the imperfect justice of our terrestrial world.

By contrast, secular people have little to hope for. They are sure that they came from nowhere--the chance product of random mutation and natural selection--and are going nowhere. They know that terrible things happen, and they don't believe there is any purpose in this. No wonder that secular people have so few children: they have much less reason than religious people to believe in the future.

So why is an atheist like Richard Dawkins so frequently wearing a conspitated scowl? And why am I usually smiling? Some may attribute these differences to our genetic temperaments. Others may put it down to the fact that I live in sunny California, eating healthy nouvelle cuisine and going on walking tours in Santorini. Dawkins, by contrast, lives in dank, rainy England and eats abominable English food. ("May I offer you some more kidney pie, Professor Dawkins? It's somewhat bland, I know, but perhaps it will work as a laxative.")

But Arthur Brooks would probably say that our temperaments are also the consequences of two very different worldviews, one producing the wholesome optimism of What's So Great About Christianity, the other the angry bitterness of The God Delusion. Read Brooks' new book yourself to see if he's right.