The focus of this paper is on the evolution of the major macroeconomic variables of classical political economy and the contrast with their orthodox counterparts in the quest to identify the causes of the current crisis in the Greek economy. Our analysis shows that declining profitability past a certain point leads to a stagnant mass of real net profits that discourage investment and increase unemployment. More specifically, for the period 1970-2007 for which we have detailed data, we identify the so-called silent depression of the 1970s and early 1980s, the new golden age of accumulation during which the capitalization of the production process led to a rapidly growing productivity and with stagnant or slowly rising real wages increased the rate of surplus value to new heights. As a consequence, the rate of profit from the mid-1980s onwards displayed a mildly rising trend and remained at a much lower level than that of the early 1970s. The rate of profit starts to fall after 2007, the year of the onset of the (world) economic crisis, and this continues up to 2014. Our econometric analysis based on an ARDL model further shows that the incremental rate of return, a variable derived from, and therefore strictly related to the average rate of profit, constitutes a by far more concrete measure of profitability and, in combination with the real interest rate, shapes the process of capital accumulation.