The main limitation of these models is their neglect of differentials within a particular social class. Thus Solow deals with a representative agent and Ricardos economy is populated by homogeneous groups of land owners, capitalists and wage earners who receive the same remuneration at the same rate. While it is important to pay attention to changes in factor shares, the empirical evidence shows that a large part of income inequality and of its evolution over time is explained by variations in the distribution of income among wage earners, rentiers and profit recipients.