But domestic animals have quite special conditions, which do not allow the assimilation of these varieties with those which have been simply produced by natural forces. Cuvier[212] had already pointed out this difference, and rejected all assimilation between them and free animals. Without taking too much account of the reasons which impelled him towards such opinions, we believe that upon this point, at least, he was entirely in the right; as to the rest, Isidore Geoffroy himself furnishes us with weapons against his own theories. “Since nature, left to herself,” he says, “does not give us witnesses of the great changes in the conditions of existence, it is clear that there only remains one means of seeing such changes, and of deducing therefrom the effects upon organisation,--it is _to force nature to do what she would not do voluntarily_.”[213] All the condemnation of this system of Isidore Geoffroy is contained, in our opinion, in these last words. As for ourselves, we reject, in the most absolute and formal manner, the connexion which some have desired to make between man and the domestic animals. Man is a sociable animal, like many others; but he only becomes exceptionally a domestic animal when he falls into slavery. The domestic animal is a being drawn from the normal state, and constrained by man. He is constrained by nature to obey the influence of his master alone,--an influence infinitely variable. It resembles itself no longer; the habit of obedience does not even leave it its will; it ceases to be a personality, and becomes a mere machine, producing for the benefit of another person. Domesticity has certain characteristics of degeneracy; the animal loses its activity, it becomes less eager, and assimilates itself more; it becomes almost incapable of subsisting alone; it vegetates; together with its personality it has lost this resistance to the ambient medium, which is the necessary characteristic of the species, the condition of the _nisus formativus_; it modifies itself to everybody’s will. Its organism may be considered as being in a state of unstable equilibrium, so that the least influence causes this organism to vary, and with the least possible delay, to a considerable degree.[214] But when man ceases for an instant to be attentive in directing these modifications, when he forgets himself for a moment, nature--always vigilant and ready to seize upon her rights--destroys all this human edifice, and recalls the animal to a type which may be called normal, but which is not the type of the stock, since nature, acting on an organism endowed, as we have just said, with the wonderful malleability and ductility acquired by domesticity, immediately and naturally modifies the animal, which is restored to liberty, by the power of the new medium into which it is cast.