"But we cannot know Nature by inclosing her action within the narrow circle of our own thoughts.... Instead of limiting her action, we should extend it through immensity itself; we should regard nothing as impossible, but should expect to find all things—supposing that all things are possible—nay, are. Doubtful species, then, irregular productions, anomalous existences will henceforth no longer surprise us, and will find their place in the infinite order of things as duly as any others. They fill up the links of the chain; they form knots and intermediate points, and also they mark its extremities: they are of especial value to human intelligence, as providing it with cases in which Nature, being less in conformity with herself, is taken more unawares, so that we can recognize singular characters and fleeting traits which show us that her ends are much more general than are our own views of those ends, and that, though she does nothing in vain, yet she does but little with the designs which we ascribe to her."[84]
"The pig," he continues, "is not formed on an original, special, and perfect type; its type is compounded of that of many other animals. It has parts which are evidently useless, or which at any rate it cannot use—such as toes, all the bones of which are perfectly formed but which are yet of no service to it. Nature then is far from subjecting herself to final causes in the composition of her creatures. Why should she not sometimes add superabundant parts, seeing she so often omits essential ones?" "How many animals are there not which lack sense and limbs? Why is it considered so necessary that every part in an individual should be useful to the other parts and to the whole animal? Should it not be enough that they do not injure each other nor stand in the way of each other's fair development? All parts coexist which do not injure each other enough to destroy each other, and perhaps in the greater number of living beings the parts which must be considered as relative, useful, or necessary, are fewer than those which are indifferent, useless, and superabundant. But we—ever on the look out to refer all parts to a certain end—when we can see no apparent use for them suppose them to have hidden uses, and imagine connections which are without foundation, and serve only to obscure our perception of Nature as she really is: we fail to see that we thus rob philosophy of her true character, which is to inquire into the 'how' of things—into the manner in which Nature acts—and that we substitute for this true object a vain idea, seeking to divine the 'why'—the ends which she has proposed in acting."[85]
The Dog—Varieties in consequence of Man's Selection.
"Of all animals the dog is most susceptible of impressions, and becomes most easily modified by moral causes. He is also the one whose nature is most subject to the variations and alterations caused by physical influences: he varies to a prodigious extent, in temperament, mental powers, and in habits: his very form is not constant;" ... but presents so many differences that "dogs have nothing in common but conformity of interior organization, and the power of interbreeding freely."...
... "How then can we detect the characters of the original race? How recognize the effects produced by climate, food, &c.? How, again, distinguish these from those other effects which come from the intermixture of races, either when wild or in a state of domestication? All these causes, in the course of time, alter even the most constant forms, so that the imprint of Nature does not preserve its sharpness in races which man has dealt with largely. Those animals which are free to choose climate and food for themselves can best conserve their original character, ... but those which man has subjected to his own influence—which he has taken with him from clime to clime, whose food, habits, and manner of life he has altered—must also have changed their form far more than others; and as a matter of fact we find much greater variety in the species of domesticated animals than in those of wild ones. Of all these, however, the dog is the one most closely attached to man, living like man the least regular manner of life; he is also the one whose feelings so master him as to make him docile, obedient, susceptible of every kind of impression, and even of every kind of constraint; it is not surprising, then, that he should of all animals present us with the greatest variety in shape, stature, colour, and all physical and mental qualities."
Here again the direct cause of modification is given as being the inner feelings of the animal modified, change of conditions being the indirect cause as with Dr. Erasmus Darwin and Lamarck.
"Other circumstances, however, concur to produce these results. The dog is short-lived: he breeds often and freely: he is perpetually under the eye of man; hence when—by some chance common enough with Nature—a variation or special feature has made its appearance, man has tried to perpetuate it by uniting together the individuals in which it has appeared, as people do now who wish to form new breeds of dogs and other animals. Moreover, though species were all formed at the same time, yet the number of generations since the creation has been much greater in the short-lived than in the long-lived species: hence variations, alterations, and departure from the original type, may be expected to have become more perceptible in the case of animals which are so much farther removed from their original stock.
"Man is now eight times nearer Adam than the dog is to the first dog—for man lives eighty years, while the dog lives but ten. If, then, these species have an equal tendency to depart from their original type, the departure should be eight times more apparent with the dog than with man."[86]
Here follow remarks upon the great variability of ephemeral insects and of animal plants, on the impossibility of discovering the parent-stock of our wheat and of others of our domesticated plants,[87] and on the tendency of both plants and animals to resume feral characteristics on becoming wild again after domestication.[88]
The Hare—Geometrical Ratio of Increase.