In the present chapter, I question the latter claim and maintain that the possibility of output variations through changes in the actual rates of capacity utilization does not imply any special difference in the premises or assumptions to be adopted compared to those present in the analyses of the classical economists and Marx. In particular, I will argue that the opposite view is in fact an outcome of the failure to recognize changes of capacity utilization as a form of capital inflow or outflow, to be included among the effects on sectoral outputs that the classical analysis generally ascribes to the mobility of capital in response to profitability differences.