CERTAIN questions have arisen' concerning my macrodynamic theory of business cycles2 which I consider of sufficient importance to warrant a detailed answer. I also wish to complete some parts of my original study which I think were presented too briefly. 1. Tinbergen makes the statement concerning my original article that, remarkably enough, prices do not appear at all in the theory.3 It can be easily shown that in reality my basic equation implies the dependence of investment activity on the ratio of prices to wages. My basic equation was4