The overall curve and the orders of magnitude described here may be taken as reliable and significant, at least to a first approximation. Nevertheless, the limitations and weaknesses of the data should be noted immediately. First, as noted, the very notion of an “average” rate of return on capital is a fairly abstract construct. In practice, the rate of return varies widely with the type of asset, as well as with the size of individual fortunes (it is generally easier to obtain a good return if one begins with a large stock of capital), and this tends to amplify inequalities.
