"The most important misunderstanding seems to me to lie in a confusion between the human necessities which I consider part of human nature, and the human necessities as they appear as drives, needs, passions, etc., in any given historical period. This division is not very different from Marx’s concept of "human nature in general", to be distinguished from "human nature as modified in each historical period". The same distinction exists in Marx when he distinguishes between "constant" or "fixed" drives and "relative" drives. The constant drives "exist under all circumstances and … can be changed by social conditions only as far as form and direction are concerned". The relative drives "owe their origin only to a certain type of social organization"."