In 2014, soaring inequality in advanced nations finally received the attention it deserved, as Thomas Piketty’s “Capital in the Twenty-First Century” became a surprise (and deserving) best seller. The usual suspects are still in well-paid denial, but, to everyone else, it is now obvious that income and wealth are more concentrated at the very top than they have been since the Gilded Age — and the trend shows no sign of letting up.

But that’s a story about developments within nations, and, therefore, incomplete. You really want to supplement Piketty-style analysis with a global view, and when you do, I’d argue, you get a better sense of the good, the bad and the potentially very ugly of the world we live in.

So let me suggest that you look at a remarkable chart of income gains around the world produced by Branko Milanovic of the City University of New York Graduate Center (which I will be joining this summer). What Mr. Milanovic shows is that income growth since the fall of the Berlin Wall has been a “twin peaks” story. Incomes have, of course, soared at the top, as the world’s elite becomes ever richer. But there have also been huge gains for what we might call the global middle — largely consisting of the rising middle classes of China and India.

And let’s be clear: Income growth in emerging nations has produced huge gains in human welfare, lifting hundreds of millions of people out of desperate poverty and giving them a chance for a better life.