Like Malthus, Ricardo owes his reputation very largely to the theory associated with his name, though it has long ceased to be stated precisely in the terms he employed.
A note in his diary, dated the 7th of November 1749, shows that he had then 4 Malthus quoted Franklin in his first edition, but it was not until the second that he introduced the theory of the " preventive check."
Franklin noted the phenomenon with disapproval in his advocacy of increased population; Malthus with approval in his search for means to decrease population.
By the end of the century, however, owing to a great extent to the publication of the essays of Malthus, the pendulum had swung far in the opposite direction, it was thought desirable to possess the means of judging from time to time the relations between an increasing population and the means of subsistence.
Malthus expressed the opinion that only in such a land of unlimited means of living could population.