One thing which is striking in Malthus's theory is his insistence on contradictions and conflicts in the capitalist system. The system is shown not to be self-adjusting. Unless a large class of unproductive consumers was maintained, periodic over-production and stagnation would inevitably occur. For the first time, in English economic theory at any rate, the possibility of crises arising from causes inherent in the capitalist system was admitted.

Chapter V, Reaction And Revolution, p. 208 - A History of Economic Thought (1939)