Thomas malthus didn't account for what in his theory

In 1798, when Thomas Malthus published his theory in the book An Essay On The Principle of Population, he brought out that he believed that through preventative checks and positive checks, the population would be controlled to balance the food supply with the population level, but, what he did not consider was that pesticides, machines, refrigeration, and other technical advances would make it possible to feed enormous numbers of people very well.