China has directly contributed one quarter of the growth in global GDP (as measured by the IMF at purchasing power parities) thus far during the 21st century. But its trend growth rate has unambiguously slowed over this period, from an average of over 10 per cent per annum during the first decade to an average of just under 6½ per cent per annum over the past decade. And it seems set to slow further over the coming decade. This is likely to have important consequences for the growth trajectory of the world economy mainly as a matter of arithmetic, rather than economic theory.