CH. 6 THE DEFINITION OF INCOME 65

perhaps, by thinking in terms of decisions to consume(or to refrain from consuming) rather than of decisionsto save. A decision to consume or not to consumetruly lies within the power of the individual; so doesa decision to invest or not to invest.The amounts ofaggregate income and of aggregate saving are the resultsof the free choices of individuals whether or not to con-sume and whether or not to invest; but they are neitherof them capable of assuming an independent value re-sulting from a separate set of decisions taken irrespectiveof the decisions concerning consumption and invest-ment. In accordance with this principle, the con-ception of the propensity to consume will, in what follows,take the place of the propensity or disposition to save.