The fourth and last phase of the world’s history must be for us men that latest period of time which has witnessed the development of our own race. Lamarck (1809) had already recognized that this evolution is only rationally conceivable as the outcome of a natural process, by “descent from the apes,” our next of kin among the mammals. Huxley then proved, in his famous essay on The Place of Man in Nature, that this momentous thesis is an inevitable consequence of the theory of descent, and is thoroughly established by the facts of anatomy, embryology, and palæontology. He considered this “question of all questions” to be substantially answered. Darwin followed with a brilliant discussion of the question under many aspects in his Descent of Man (1871). I had myself devoted a special chapter to this important problem of the science of evolution in my General Morphology (1866). In 1874 I published my Anthropogeny, which contains the first attempt to trace the descent of man through the entire chain of his ancestry right up to the earliest archigonous monera; the attempt was based equally on the three great “documents” of evolutionary science—anatomy, embryology, and palæontology. The progress we have made in anthropogenetic research during the last few years is described in the paper which I read on “Our Present Knowledge of the Origin of Man” at the International Congress of Zoologists at Cambridge in 1898.[28]
[CHAPTER XIV]
THE UNITY OF NATURE
The Monism of the Cosmos—Essential Unity of Organic and Inorganic Nature—Carbon-Theory—The Hypothesis of Abiogenesis—Mechanical and Purposive Causes—Mechanicism and Teleology in Kant’s Works—Design in the Organic and Inorganic Worlds—Vitalism—Neovitalism—Dysteleology (the Moral of the Rudimentary Organs)—Absence of Design in, and Imperfection of, Nature—Telic Action in Organized Bodies—Its Absence in Ontogeny and Phylogeny—The Platonist “Ideas”—No Moral Order Discoverable in the History of the Organic World, of the Vertebrates, or of the Human Race—Prevision—Design and Chance
One of the first things to be proved by the law of substance is the basic fact that any natural force can be directly or indirectly converted into any other. Mechanical and chemical energy, sound and heat, light and electricity, are mutually convertible; they seem to be but different modes of one and the same fundamental force or energy. Thence follows the important thesis of the unity of all natural forces, or, as it may also be expressed, the “monism of energy.” This fundamental principle is now generally recognized in the entire province of physics and chemistry, as far as it applies to inorganic substances.
It seems to be otherwise with the organic world and its wealth of color and form. It is, of course, obvious that a great part of the phenomena of life may be immediately traced to mechanical and chemical energy, and to the effects of electricity and light. For other vital processes, however, especially for psychic activity and consciousness, such an interpretation is vigorously contested. Yet the modern science of evolution has achieved the task of constructing a bridge between these two apparently irreconcilable provinces. We are now certain that all the phenomena of organic life are subject to the universal law of substance no less than the phenomena of the inorganic universe.
The unity of nature which necessarily follows, and the demolition of the earlier dualism, are certainly among the most valuable results of modern evolution. Thirty-three years ago I made an exhaustive effort to establish this “monism of the cosmos” and the essential unity of organic and inorganic nature by a thorough, critical demonstration, and a comparison of the accordance of these two great divisions of nature with regard to matter, form, and force.[29] A short epitome of the result is given in the fifteenth chapter of my Natural History of Creation. The views I put forward are accepted by the majority of modern scientists, but an attempt has been made in many quarters lately to dispute them and to maintain the old antithesis of the two divisions of nature. The ablest of these is to be found in the recent Welt als That of the botanist Reinke. It defends pure cosmological dualism with admirable lucidity and consistency, and only goes to prove how utterly untenable the teleological system is that is connected therewith. According to the author, physical and chemical forces alone are at work in the entire field of inorganic nature, while in the organic world we find “intelligent forces,” regulative or dominant forces. The law of substance is supposed to apply to the one, but not to the other. On the whole, it is a question of the old antithesis of a mechanical and a teleological system. But before we go more fully into it, let us glance briefly at two other theories, which seem to me to be of great importance in the decision of that controversy—the carbon-theory and the theory of spontaneous generation.
Physiological chemistry has, after countless analyses, established the following five facts during the last forty years:
I. No other elements are found in organic bodies than those of the inorganic world.