Another circumstance seems to us to have been entirely overlooked, and it is one which gives the theory of selection an inevitable appearance of truth, even if it is essentially false, and thus makes it very difficult to refute. Assuming that the recognition of teleological factors is valid, that there is an inward law of development, that “Moses” or whoever one will was undoubtedly right, it is self-evident that, because of the indubitable over-production of organisms, there would even then be a struggle for existence on an immense scale, and that it would have a far-reaching “selective” influence, because of the relative plasticity of many forms of life. Beyond doubt it would, in the course of æons, have applied its shears to many forms of life, and probably there would be no organisms, organs, or associations in the evolution of the ultimate form of which it had not energetically co-operated. Its influence would, perhaps, be omnipresent, yet it might be far from being the all-sufficient factor in evolution; indeed, as far as the actual impulse of evolution is concerned, it might be a mere accessory. Unless we are to think of the forms of life as wholly passive and wooden, the struggle for existence must necessarily be operative, and the magnitude of its results, and their striking and often bizarre outcome, will tend ever anew to conceal the fact that the struggle is after all only an inevitable accompaniment of evolution. And thus we understand how it is that interpretations from the point of view of an inward law of development, of orthogenesis, or of teleology, notwithstanding their inherent validity, have _à priori_ always had a relatively difficult position as compared with the Darwinian view.
It is usual to speak of the “all-sufficiency of natural selection,” yet the champion of the selection-theory admits, as he needs must, that the struggle for existence and selection can of themselves create absolutely nothing, no new character, no new or higher combination of the vital elements; they can only take what is already given; they can only select and eliminate among the wealth of what is offered.(38) And the offerer is Life itself by virtue of its mysterious capacity for boundless and inexhaustible variability, self-enrichment and increase. The “struggle for existence” only digs the bed through which life’s stream flows, draws the guiding-line, and continually stimulates it to some fresh revelation of its wealth. But this wealth was there from the beginning; it was, to use the old word, “potential” in the living, and included with it in the universal being from which life was called forth. The struggle for existence is only the steel which strikes the spark from the flint; is, with its infinite forms and components, only the incredibly complex channel through which life forces its way upwards. If we keep this clearly in mind, the alarming and ominous element in the theory shrinks to half its dimensions.