The Marxist concept of private property gives the basis for Marx's theory. "Private property" in the terminology of Marx's time, for Marx himself, and for Marxists sometimes today, does not mean the simple possessions of a person, but the ownership of productive property or property which produces a profit for the owner,[3] such as corporate ownership, share ownership, land ownership, and—in the case of slave society—slave ownership (since slaves work the land, mines and other means of producing the material means of existence).