The whole nexus of conditions and results, the inclined plane of evolution and the power of Being to move up it, has its sufficient reason in the nature and original state of the cosmos, in the constitution of its “matter,” its “energy,” its laws, its sequences and the grouping of its phenomena. Only from beginnings so constituted could our present world have come to be as it is, and that necessarily. Only because the primary possibility and fitness for life—vegetable, animal and human—was in it from the beginning, could all these have come to be. This primary possibility did not “come into being,” it was _à priori_ immanent in it. Whence came this? There is no logical, comprehensible, or any other necessity why there should be a world at all, or why it should be such that life and evolution must become part of it. Where then lies the reason why it is, rather than is not, and why it is as it is?
To this must be added what Weismann himself readily admits and expressly emphasises. The whole theory treats, and must treat plant, animal, and man as only ingenious machines, mere systems of physical processes. This is the ideal aimed at—to interpret all the phenomena of life, growth, and reproduction thus. Even instincts and mental endowments are so interpreted, since there must be corresponding morphological variations of the fine structure of the nervous organ, and instinctive actions are then “explained” as the functions of these. But how “mechanical happening” comes to have this marvellous inwardness, which we call sensation, feeling, perception, thought and will, which is neither mechanical nor derivable from anything mechanical; and, further, how physical and psychical can condition one another without doing violence to the law of the conservation of the sum of energy, is an absolute riddle. But this whole psychical world exists, with graduated stages perhaps as close to each other as in the physical world, but even less capable than these of being explained as having arisen out of their antecedent lower stages. And this psychical world, which is, indeed, related to and dependent upon the corporeal life, as also conversely, has its own quite peculiar laws: thought does not follow natural laws, but those of logic, which is entirely indifferent to exciting stimuli, for instance of the brain, which conform to natural laws. But this world, its riddles and mysteries, its great content and its history, beyond the reach of mechanical theories, is so absolutely the main thing (especially in regard to the question of the possibility of religion), that the question of bodily structure and evolution becomes beside it a mere accessory problem, and even the last is only a relatively unimportant roundabout way of coming at the gist of the business. How completely the evolution of the higher mental faculties transcends such narrow and meagre formulæ as the struggle for existence and the like, Weismann himself indicates in connection with man’s musical sense, and its relation to the “musical” instinct in animals. The same and much more might be alleged in regard to the whole world of mind, of the æsthetic, ethical and religious, of the kingdom of thought, of science, and of poetry.