“Making men and women all equal. That I take to be the gist of our political theory.” This rejoinder to rightwingers who delight in rank and privilege is due to the free-spirited Liberal heroine of Trollope’s Phineas Finn, Lady Glencora. It encapsulates the cardinal error of much of the left.

Joshua Monk, one of the novel’s Radicals, sees through it. “Equality is an ugly word…and frightens,” he says. The aim of the true Liberal should not be equality but “lifting up those below him.” It is to be achieved not by redistribution but by free trade and compulsory education and women’s rights.

And it came to pass. In the UK since 1800, or Italy since 1900, or Hong Kong since 1950, real income per head has increased by a factor of anywhere from 15 to 100, depending on how one allows for the improved quality of steel girders and plate glass, medicine and economics.

In relative terms, the poorest people in the developed economies and billions in the poor countries have been the biggest beneficiaries. The rich became richer, true. But the poor have gas heating, cars, smallpox vaccinations, indoor plumbing, cheap travel, rights for women, low child mortality, adequate nutrition, taller bodies, doubled life expectancy, schooling for their kids, newspapers, a vote, a shot at university and respect.

Never had anything similar happened, not in the glory of Greece or the grandeur of Rome, not in ancient Egypt or medieval China. What I call The Great Enrichment is the main fact and finding of economic history.

Yet you will have heard that our big problem is inequality, and that we must make men and women all equal. No, we should not—at least, not if we want to lift up the poor.

Ethically speaking, the true liberal should care only about whether the poorest among us are moving closer to having enough to live with dignity and to participate in a democracy. They are. Even in already rich countries, such as the UK and the US, the real income of the poor has recently risen, not stagnated—if, that is, income is correctly measured to include better healthcare, better working conditions, more years of education, longer retirements and, above all, the rising quality of goods. Admittedly, it is rising at a slower pace than in the 1950s; but that era of rising prosperity followed the wretched setbacks of the Great Depression and the war.

It matters ethically, of course, how the rich obtained their wealth—whether from stealing or from choosing the right womb (as the billionaire investor Warren Buffett puts it); or from voluntary exchanges for the cheap cement or the cheap air travel the now-rich had the good sense to provide the once-poor. We should prosecute theft and reintroduce heavy inheritance taxes. But we should not kill the goose that laid the golden eggs.

What does not matter ethically are the routine historical ups and downs of the Gini coefficient, a measure of inequality, or the excesses of the 1 per cent of the 1 per cent, of a sort one could have seen three centuries ago in Versailles. There are not enough really rich people. If we seized the assets of the 85 wealthiest people in the world to make a fund to give annually to the poorest half, it would raise their spending power by less than 4p a day.

All the foreign aid to Africa or South and Central America, for example, is dwarfed by the amount that nations in these areas would gain if the rich world abandoned tariffs and other protections for their agriculture industries. There are ways to help the poor—let the Great Enrichment proceed, as it has in China and India—but charity or expropriation are not the ways.

The Great Enrichment came from innovation, not from accumulating capital or exploiting the working class or lording it over the colonies. Capital had little to do with it, despite the unhappy fact that we call the system “capitalism.” Capital is necessary. But so is water, labour, oxygen and pencils. The path to prosperity involves betterment, not piling brick on brick.

Taxing the rich, or capital, does not help the poor. It can throw a spanner into the mightiest engine for lifting up those below us, arising from a new equality, not of material worth but of liberty and dignity. Gini coefficients are not what matter; the Great Enrichment is.