Topic summary
Labor power

Extracted from the Wikipedia article Labour power.
The value of labor power
Labour power is a peculiar commodity, because it is an attribute of living persons, who own it themselves in their living bodies. Because they own it within themselves, they cannot permanently sell it to someone else; in that case, they would be a slave, and a slave does not own himself. Yet, although workers can hire themselves out, they cannot "hire out" or "lease" their labour, since they cannot reclaim or repossess the labour at some point after the work is done, in the same way as rental equipment is returned to the owner. Once labour has been expended, it is gone, and the only remaining issue is who benefits from the results, and by how much.