who did not sin, "neither was deceit found in his mouth."

 It was by no means only menial tasks which were performed by slaves. Doctors, teachers, musicians, actors, secretaries, stewards were slaves. In fact, all the work of Rome was done by slaves. Roman attitude was that there was no point in being master of the world and doing one's own work. Let the slaves do that and let the citizens live in pampered idleness. The supply of slaves would never run out. 