Let me now turn to the consequences of r > g for the dynamics of the wealth distribution. The fact that
the return on capital is distinctly and persistently greater than the growth rate is a powerful force for a
more unequal distribution of wealth. For example, if g = 1 percent and r = 5 percent, wealthy
individuals have to reinvest only one-fifth of their annual capital income to ensure that their capital
will grow faster than average income. Under these conditions, the only forces that can avoid an
indefinite inegalitarian spiral and stabilize inequality of wealth at a finite level are the following.
First, if the fortunes of wealthy individuals grow more rapidly than average income, the
capital/income ratio will rise indefinitely, which in the long run should lead to a decrease in the rate
of return on capital. Nevertheless, this mechanism can take decades to operate, especially in an open
economy in which wealthy individuals can accumulate foreign assets, as was the case in Britain and
France in the nineteenth century and up to the eve of World War I. In principle, this process always
comes to an end (when those who own foreign assets take possession of the entire planet), but this can
obviously take time. This process was largely responsible for the vertiginous increase in the top
centile’s share of wealth in Britain and France during the Belle Époque.