Peter Kropotkine, The wage system (1920)
“ The middle-class economists, and Marx too, will be cited to prove that there is a good reason for a scale of wages, for the "labor force" of the engineer costs society more than the "labor force" of the navvy. And, indeed, have not the economists striven to prove that, if the engineer is paid twenty times more than the navvy, it is because the cost necessary to produce an engineer is more considerable than that necessary to produce a navvy? And has not Marx maintained that the like distinction between various sorts of manual labor is of equal logical necessity? ”
