The Malthus model of economic growth (or the lack thereof) is now standard fare in undergraduate education. Basically, it shows that there is a limit to the size of an economy that hinges on decreasing returns to labor in production and on mortality increasing as standards of living, as measured by GDP per capita, decrease. Those two critical assumptions are based on observations that were certainly valid at Malthus' times, and are likely to still be true today.
Carl-Johan Dalgaard and Holger Strulik go a little bit further in this theory. As more food is available, people grow taller. But being tall requires more food to sustain the body, which provides an additional reason for stagnation. This makes it more difficult to break loose from this "development trap" and may explain why economies stagnated for so long. But as Malthusian theory, this dies not explain why the economy suddenly exploded in the 19th century.