Another strand of opposition to Malthus's ideas started in the middle of the 19th century with the writings of Friedrich Engels ("Outlines of a Critique of Political Economy", 1844) and Karl Marx ("Capital", 1867). Engels and Marx argued that what Malthus saw as the problem of the pressure of population on the means of production actually represented the pressure of the means of production on population. They thus viewed it in terms of their concept of the reserve army of labour. In other words, the seeming excess of population that Malthus attributed to the seemingly innate disposition of the poor to reproduce beyond their means actually emerged as a product of the very dynamic of capitalist economy.