In comparing man with the animal we find in both an organized body, senses, flesh, blood, motion, and a multitude of other resemblances. But these resemblances are all external, and not sufficient to justify a decision, that the human and the animal natures are similar. In order to form a proper judgment of the nature of each we ought to have as distinct a knowledge of the internal qualities of an animal as we have of our own. As the knowledge of what passes within animals is impossible to be attained, and as we know not of what order and kind its sensations may be, in relation to those of man, we can only judge from a comparison of the effects which result from the natural operations of both. Let us, then, take a view of these effects; and, while we admit of all the particular resemblances, limit our investigation to the most general distinctions. It will be allowed, that the most stupid man is able to manage the most acute animal; he governs it, and renders if subservient to his purposes; and this, not so much on account of his strength or skill as by the superiority of his nature, and from his being possessed of reason, which enables him to form a rational system of action and method, by which he compels the animals to obey him. The strongest and most acute animals do not give law to the inferior, nor hold them in servitude. The stronger, it is true, devour the weaker, but this action implies no more than an urgent necessity, or a rage of appetite; qualities very different from that which produces a series of actions, all tending to the same end. Did animals enjoy this faculty, should we not see some of them assume dominion over others, and oblige them to furnish their food, to watch over them, and to attend them when sick or wounded? Now, throughout the creation of animals, there is no vestige of such subordination, no appearance that one of them knows, or is sensible of, the superiority of his own nature over that of others. It follows, then, that they must all be considered as of one nature, and that the nature of man is not only highly superior to that of the brute, but also entirely different from it.