Capital gains and net national product in open economies

It is shown within a given framework that, with the world economy following an egalitarian path, the aggregate capital gains being positive is equivalent to the interest rate tending to decrease. This result is of importance for the concept of net national product in open economies. In particular, with positive aggregate capital gains, an open economy cannot sustain consuming the return on its capital stocks, since some part of the return must be used to augment the country's national wealth. It is established that a country's share of world-wide sustainable consumption equals its share of worldwide wealth.