It is known that human labor is able to produce more than it consumes, and this capacity for  “surplus labor” is sometimes treated as a special and mystical endowment of humanity or of its labor.  In reality it is nothing of the sort, but is merely the prolongation of working time beyond the point where labor has reproduced itself, or in other words brought into being its own means of subsistence or their equivalent.  This time will vary with the intensity and productivity of labor, as well as with the changing requirements of “subsistence,” but for any given state of these it is a definite duration.  The “peculiar” capacity of labor power to produce for the capitalist after it has reproduced itself is therefor nothing but the extension of work time beyond the point where it could otherwise come to a halt.  An ox too will have this capacity, and grind out more corn than it will eat if kept to the task by training and compulsion (38).