In Keynes’ General Theory, the political economy of time is introduced in, at least, two ways. First, Keynes reverses the causality between investment and savings, basing his view on the temporal priority of the former. Second, having a radically different concept of the nature, importance and function of time, the investment decision-making prosses is redefined, in an attempt to approach reality, bypassing the analytical ease of the positivist calculus, so vividly used by mainstream theory. Section 2 introduces the concept of the marginal efficiency of capital (MEC) as it plays an important role in interpreting the major macroeconomic trends of the capitalist economies. Section 3 offers literature findings to indicate the early reception of Keynes’s ideas by a contemporary group of heterodox thinkers, emphasizing the character of a distant affinity between the Keynesian and Marxist thought. Section 4 addresses the importance of time and the terminology underpinning uncertainty in economic theory while Section 5, focuses on the distinction between short-term and long-term expectations, explaining why the GT does not fall within the conventional analysis of general equilibrium.