China is now number two in the world in GDP, having just passed Japan. As the Wall Street Journal reports this morning, its 2nd-quarter GDP was $1.339 trillion, while Japan racked up $1.288 trillion. It has been number two for a quarter before, but only in the 4th quarter, which is always a good one for China.

With China’s passing Japan in the 2nd quarter, it looks likely that it will surpass Japan for the entire year. With their differential growth rates, China will then be firmly in second place in total GPD. On a per-capita GDP basis, of course, China remains far behind Japan as well as Germany, France, and Britain (fourth, fifth, and sixth, respectively). If present trends continue (which they never do), China would pass the United States in total GDP in another few decades.

But if it does, China would only be returning to its former status as the world’s leading economy, which it was for centuries. It was only when the Industrial Revolution transformed Western economies (and Western militaries) in the early 19th century that China under the Ching (or Ch’ing or Quing — take your pick) dynasty sank into decay and it lost its place.

It is an old axiom of geopolitics that “Great Powers shuffle on and off the stage of history noisily.” And China’s return to being one of the main engines of the world economy is likely to be noisy, with profound implications for the balance of power. China is already asserting itself in its neighborhood and elsewhere, and its military is growing quickly in both reach and capacity. It’s new naval strategy has shifted from coastal defense to “far sea defense.”

But as China’s population gets richer, better educated, and more widely familiar with the world outside its borders, it is undoubtedly going to demand more and more say in the running of the country. Already there has been a lot of labor unrest and demonstrations, which are probably considerably underreported. The current system, which gives people a lot of economic freedom but little political freedom (or the protection of the rule of law), is unlikely to be sustainable in the long run.

China has come a long, long way in an astonishingly short period of time, but it has a long way to go before it is the equal of the other Great Powers in anything but economic clout.