Inequality of financial wealth goes up and down, but over the long term it has been reduced. Financial inequality was greater in 1800 and 1900 than it is now, as even the French economist Thomas Piketty has acknowledged. By the more important standard of basic comfort in consumption, inequality within and between countries has fallen nearly continuously.

In any case, the problem is poverty, not inequality as such — not how many yachts the L’Oréal heiress Liliane Bettencourt has, but whether the average Frenchwoman has enough to eat. At the time of “Les Misérables,” she didn’t. In the last 40 years, the World Bank estimates, the proportion of the population living on an appalling $1 or $2 a day has halved. Paul Collier, an Oxford economist, urges us to help the “bottom billion” of the more than seven billion people on earth. Of course. It is our duty. But he notes that 50 years ago, four billion out of five billion people lived in such miserable conditions. In 1800, it was 95 percent of one billion.

We can improve the conditions of the working class. Raising low productivity by enabling human creativity is what has mainly worked. By contrast, taking from the rich and giving to the poor helps only a little — and anyway expropriation is a one-time trick. Enrichment from market-tested betterment will go on and on and, over the next century or so, will bring comfort in essentials to virtually everyone on the planet, and more to an expanding middle class.

Look at the astonishing improvements in China since 1978 and in India since 1991. Between them, the countries are home to about four out of every 10 humans. Even in the United States, real wages have continued to grow — if slowly — in recent decades, contrary to what you might have heard. Donald Boudreaux, an economist at George Mason University, and others who have looked beyond the superficial have shown that real wages are continuing to rise, thanks largely to major improvements in the quality of goods and services, and to nonwage benefits. Real purchasing power is double what it was in the fondly remembered 1950s — when many American children went to bed hungry.

What, then, caused this Great Enrichment?

Not exploitation of the poor, not investment, not existing institutions, but a mere idea, which the philosopher and economist Adam Smith called “the liberal plan of equality, liberty and justice.” In a word, it was liberalism, in the free-market European sense. Give masses of ordinary people equality before the law and equality of social dignity, and leave them alone, and it turns out that they become extraordinarily creative and energetic.