We have seen that human labor power is enabled at a very early stage of production to produce considerably more than is needed to maintain the producer. We have found that this stage coïncided in general with the first appearance of the division of labor and of exchange between individuals. Now, it was not long before the great truth was discovered that man may himself be a commodity, and that human labor power may be exchanged and exploited by transforming a man into a slave. Hardly had exchange between men been established, when men themselves were also exchanged. The active asset became a passive liability, whether man wanted it or not.
Slavery, which reaches its highest development in civilization, introduced the first great division of an exploited and an exploiting class into society. This division continued during the whole period of civilization. Slavery is the first form of exploitation, characteristic of the antique world. Then followed feudalism in the middle ages, and wage labor in recent times. These are the three great forms of servitude, characteristic of the three great epochs of civilization. Their invariable mark is either open or, in modern times, disguised slavery.
The stage of commodity production introducing civilization is marked economically by the introduction of (1) metal coins and, thus, of money as capital, of interest, and of usury; (2) merchants as middlemen between producers; (3) private property and mortgage; (4) slave labor as the