What was Thomas Malthus' theory on the limits of growth?

Economic growth is limited to the land's fertility

People pay too much attention to the "Essay on Population", and forget about Malthus' "Principles of Political Economy". In this book, you will find out that a malthusian production function considers work and capital as complementaries, rather than substitutes. To Malthus, for a given quantity of capital, there is a necessary quantity of labor. Malthus says that the stock of capital can grow without limits, but not the labor pool (because of the well known principle of population). Hence, economic growth will be limited in the long run by the limited amount of labor the land can sustain.