The scientific problem is explaining modern economic growth is its astonishing magnitude-anywhere from a 3,000 to a 10,000 percent increase in real income, a "Great Enrichment." Investment, reallocation, property rights, exploitation cannot explain it. Only the bettering of betterment can, the stunning increase in new ideas, such as the screw propeller on ships or the ball bearing in machines, the modern university for the masses and careers open to talent. Why, then, the new and trade-tested ideas? Because liberty to have a go, as the English say, and a dignity to the wigmakers and telegraph operators having the go made the mass of people bold. Equal liberty and dignity for ordinary people is called "liberalism," and it was new to Europe in the eighteenth century, against old hierarchies. Why the liberalism? It was not deep European superiorities, but the accidents of the Four R's of (German) Reformation, (Dutch) Revolt, (American and French) Revolution, and (Scottish and Scandinavian) Reading. It could have gone the other way, leaving, say, China to have the Great Enrichment, much later. Europe, and then the world, was lucky after 1900. Now China and India have adopted liberalism (in the Chinese case only in the economy), and are catching up.