Again, a phenomenon of organisms that Darwin appealed to in elaborating his hypothesis is their prodigality in generation. He almost always looked at this from the standpoint of the inevitable crowding and struggle, carnage, famine and death, that result.
But there is another direction from which this prodigality must be viewed, namely, from that of the absolute interdependence, the reciprocal relationships that prevail among organisms. Though always consumers, organisms are likewise always producers, and are producers in larger measure titan is necessary for their own perpetuity and best interests. "Every species is its own worst enemy." There is consequently, on the whole, a surplusage of product as regards both the individual and the kind. So it comes about that the consumption that is going on is in part a consumption of surplus. Do not understand me to say that this is the correct view of the matter while the other is incorrect. Both views are true, and hence exclusive or unbalanced attention to either is inadequate.
Our conclusion amounts to this: Darwin's fame will grow in luster parsi passu with growing recognition that he did not discover the cause of evolution. This paradoxical statement ought to be viewed askance, as all paradoxes should be. But see its justification. We biologists will be able to approach the important truth of struggle in animate nature with minds open for evidence of every sort as to its meaning when we shall have broken up the habit—for habit it has surely become—of attributing to it powers and capabilities beyond those it actually has.
We turn again to the greater side of Darwin's work. Transform yourself in imagination to a state of mind that holds all the natural kinds of plants and animals by which you are daily surrounded, to be each an independent miraculous creation, to be objects, that is, concerning the origin of which no human being shall ever gain the slightest real knowledge. Thus transform yourself, and then, and only then, may you grasp the momentous significance of the extension of the domain of law in the physical world wrought by the establishment of the "mere fact" of evolution.
Since my position makes so much of the distinction between establishing the truth of evolution and discovering the adequate cause of evolution I must justify myself more fully. Let us ask how sharply Darwin himself made this distinction, and how he appraised his own work from this standpoint.
That Darwin was convinced of the fact of descent with modification before he had any working hypothesis as to its cause, in other words, that he was an evolutionist before he was a natural selectionist has not been given due weight, though perhaps is well enough known. Let us look briefly at the evidence for this statement.
