“A man in chains need not be a slave. If he has pride and self-respect he is a free man though a prisoner, and a constant danger to his jailers. Conversely, a slave who escapes is not a free man, but a runaway slave who may be caught and returned to servitude. A slave is one who accepts the identity ascribed to him by a master: “You are an inferior and unworthy person and so will remain, and therefore must serve me with obedience and humility.”