Even today, some people imagine, as Pareto did, that the distribution of wealth is rock stable, as if
it were somehow a law of nature. In fact, nothing could be further from the truth. When we study
inequality in historical perspective, the important thing to explain is not the stability of the distribution
but the significant changes that occur from time to time. In the case of the wealth distribution, I have
identified a way to explain the very large historical variations that occur (whether described in terms
of Pareto coefficients or as shares of the top decile and centile) in terms of the difference r − g
between the rate of return on capital and the growth rate of the economy