Indeed, once the rate of return on capital significantly and durably exceeds the growth rate, the
dynamics of the accumulation and transmission of wealth automatically lead to a very highly
concentrated distribution, and egalitarian sharing among siblings does not make much of a difference.
As I mentioned a moment ago, there are always economic and demographic shocks that affect the
trajectories of individual family fortunes. With the aid of a fairly simple mathematical model, one can
show that for a given structure of shocks of this kind, the distribution of wealth tends toward a longrun
equilibrium and that the equilibrium level of inequality is an increasing function of the gap r − g
between the rate of return on capital and the growth rate. Intuitively, the difference r − g measures the
rate at which capital income diverges from average income if none of it is consumed and everything is
reinvested in the capital stock. The greater the difference r − g, the more powerful the divergent
force. If the demographic and economic shocks take a multiplicative form (i.e., the greater the initial
capital, the greater the effect of a good or bad investment), the long-run equilibrium distribution is a
Pareto distribution (a mathematical form based on a power law, which corresponds fairly well to
distributions observed in practice). One can also show fairly easily that the coefficient of the Pareto
distribution (which measures the degree of inequality) is a steeply increasing function of the
difference r − g