Capital, vol. 3, chapter 47: "The possibility is here presented for definite economic development taking place, depending, of course, upon favourable circumstances, inborn racial characteristics, etc."
Engels: (Marx and Engels, Selected Works, Vol. 3, p. 502.): "We regard economic conditions as the factor which ultimately determines historical development. But race is itself an economic factor".
A commodity seems at first glance to be a self-evident, trivial thing. The analysis of it yields the insight that it is a very vexatious thing, full of metaphysical subtlety and theological perversities . . "
Capital, vol. 1, chap. 1, sec. 4
Marx comparing the world of commodities to religion, where the products of the human brain appear as independent beings endowed with life
Karl Marx, Capital, Volume One, Part II: The Transformation of Money and Capital CHAPTER FOUR: THE GENERAL FORMULA FOR CAPITAL: "The capitalist knows that all commodities, however scurvy they may look, or however badly they may smell, are in faith and in truth money, inwardly circumcised Jews . . ."
Suffer the children
A general prohibition of child labor is incompatible with the existence of large-scale industry and hence an empty, pious wish. Its realization -- if it were possible -- would be reactionary . . . "
https://www.marxists.org/archive/marx/works/1875/gotha/append.htm