Beavers bred in captivity, inhabiting a concrete pool, will, if given the timber, fatuously go through all the motions of damming an ancestral stream.

I have enough to do in life. I am beavering away as hard as I can for most of my waking hours and the idea that I have to keep telling people what I am doing and catching up with what they are doing is absurd.

Natural historians tend to avoid tendentious preaching in this philosophical mode (although I often fall victim to such temptations in these essays). Our favored style of doubting is empirical: if I wish to question your proposed generality, I will search for a counterexample in flesh and blood. Such counterexamples exist in abundance, for the form a staple in a standard genre of writing in natural history–the “wonderment of oddity” or “strange ways of the beaver” tradition.

So long as the fur of the beaver was extensively employed as a material for fine hats, it bore a very high price, and the chase of this quadruped was so keen that naturalists feared its speedy consideration. When a Parisian manufacturer invented the silk hat, which soon came into almost universal use, the demand for beavers' fur fell off, and this animal–whose habits, as we have seen, are an important agency in the formation of bogs and other modifications of forest nature–immediately began to increase, reappeared in haunts which we had long abandoned, and can no longer be regarded as rare enough to be in immediate danger of extirpation. Thus the convenience or the caprice of Parisian fashion has unconsciously exercised an influence which may sensibly affect the physical geography of a distant continent.

The 'stream' we call science always flows forward; sometimes reactionary beavers block its flow, but the stream is never defeated by this; it accumulates, gathers strength; its waters get over the barrage and continue on their course. The advancement of science is the advancement of God, for science is nothing but human intelligence, and human intelligence is the most valuable treasure God has bequeathed us.

The beaver is an animal which has feet like those of a goose for swimming and front teeth like a dog, since it frequently walks on land. It is called the castor from “castration,” but not because it castrates itself as Isodore says, but because it is especially sought for castration purposes. As has been ascertained frequently in our regions, it is false that when it is bothered by a hunter, it castrates itself with its teeth and hurls its musk [castoreum] away and that if one has been castrated on another occasion by a hunter, it raises itself up and shows that it lacks its musk.

The bird which is drawn to the water by its need of finding there the prey on which it lives, separates the digits of its feet in trying to strike the water and move about on the surface. The skin which unites these digits at their base acquires the habit of being stretched by these continually repeated separations of the digits; thus in course of time there are formed large webs which unite the digits of ducks, geese, etc., as we actually find them. In the same way efforts to swim, that is to push against the water so as to move about in it, have stretched the membranes between the digits of frogs, sea-tortoises, the otter, beaver, etc.
On the other hand, a bird which is accustomed to perch on trees and which springs from individuals all of whom had acquired this habit, necessarily has longer digits on its feet and differently shaped from those of the aquatic animals that I have just named. Its claws in time become lengthened, sharpened and curved into hooks, to clasp the branches on which the animal so often rests.
We find in the same way that the bird of the water-side which does not like swimming and yet is in need of going to the water's edge to secure its prey, is continually liable to sink into the mud. Now this bird tries to act in such a way that its body should not be immersed in the liquid, and hence makes its best efforts to stretch and lengthen its legs. The long-established habit acquired by this bird and all its race of continually stretching and lengthening its legs, results in the individuals of this race becoming raised as though on stilts, and gradually obtaining long, bare legs, denuded of feathers up to the thighs and often higher still.

There are hidden contradictions in the minds of people who “love Nature” while deploring the “artificialities” with which “Man has spoiled ‘Nature.’” The obvious contradiction lies in their choice of words, which imply that Man and his artifacts are not part of “Nature”—but beavers and their dams are.