In Agamben's The Use of Bodies we find the following passage:
The anthropology that we have inherited from classical philosophy is modeled on the free man. Aristotle developed his idea of the human being starting from the paradigm of the free man, even if this latter implies the slave as his condition of possibility. One can imagine that he could have developed an entirely other anthropology of he had taken account of the slave (whose "humanity" he never intended to negate). This means that, in Western culture, the slave is something like the repressed. The reemergence of the figure of the slave in the modern worker thus appears, according to the Freudian scheme as a return of the repressed in a pathological form.