We find so great a thinker as Aristotle seriously pondering, in his “Ethics,” whether a slave may be considered as a fellow-being. In emphasizing the point that friendship is founded on propinquity, he expresses himself as follows: “Neither can men have friendships with horses, cattle, or slaves, considered merely as such; for a slave is merely a living instrument, and an instrument a lifeless slave. Yet, considered as a man, a slave may be an object of friendship, for certain rights seem to belong to all those capable of participating in law and engagement.” Slaves, says Bentham, “have been treated by the law exactly upon the same footing as in England, for example, the inferior races of animals are still. The day may come when the rest of the animal creation may acquire those rights which could never have been withholden from them but by the hand of tyranny.” Let us unreservedly admit the immense difficulties that stand in the way of this animal enfranchisement. Our relation towards the animals is complicated and embittered by innumerable habits handed down through centuries of brutality and mistrust; we cannot, in all cases, suddenly relax these habits, or do full justice even where we see that justice will have to be done. A perfect ethic of humaneness is therefore impracticable, if not unthinkable; and we can attempt to do no more than to indicate in a general way the main principle of animals’ rights, noting at the same time the most flagrant particular violations of those rights, and the lines on which the only valid reform can hereafter be effected. But, on the other hand, it may be remembered, for the comfort and encouragement of humanitarian workers, that these obstacles are, after all, only such as are inevitable in each branch of social improvement; for at every stage of every great reformation it has been repeatedly argued, by indifferent or hostile observers, that further progress is impossible; indeed, when the opponents of a great cause begin to demonstrate its “impossibility,” experience teaches us that that cause is already on the high road to fulfilment.