If we contemplate the common life and the mutual relations between plants and animals (man included), we shall find everywhere, and at all times, the very opposite of that kindly and peaceful social life which the goodness of the Creator ought to have prepared for his creatures—we shall rather find everywhere a pitiless, most embittered Struggle of All against All. Nowhere in nature, no matter where we turn our eyes, does that idyllic peace, celebrated by the poets, exist; we find everywhere a struggle and a striving to annihilate neighbours and competitors. Passion and selfishness—conscious or unconscious—is everywhere the motive force of life. The well-known words of the German poet—
“Die Welt ist vollkommen überall Wo der Mensch nicht hinkommt mit seiner Qual.”[1]
are beautiful, but, unfortunately, not true. Man in this respect certainly forms no exception to the rest of the animal world. The remarks which we shall have to make on the theory of “Struggle for Existence” will sufficiently justify this assertion. It is, in fact, Darwin who has placed this important point, in its high and general significance, very clearly before our eyes, and the chapter in his theory which he himself calls “Struggle for Existence” is one of the most important parts of it.
Whilst, then, we emphatically oppose the vital or teleological view of animate nature which presents animal and vegetable forms as the productions of a kind Creator, acting for a definite purpose, or of a creative, natural force acting for a definite purpose, we must, on the other hand, decidedly adopt that view of the universe which is called the mechanical or causal. It may also be called the monistic, or single-principle theory, as opposed to the twofold principle, or dualistic theory, which is necessarily implied in the teleological conception of the universe. The mechanical view of nature has for many years been so firmly established in certain domains of natural science, that it is here unnecessary to say much about it. It no longer occurs to physicists, chemists, mineralogists, or astronomers, to seek to find in the phenomena which continually appear before them in their scientific domain the action of a Creator acting for a definite purpose. They universally, and without hesitation, look upon the phenomena which appear in their different departments of study as the necessary and invariable effects of physical and chemical forces which are inherent in matter. Thus far their view is purely materialistic, in a certain sense of that “word of many meanings.”
When a physicist traces the phenomena of motion in electricity or magnetism, the fall of a heavy body, or the undulations in the waves of light, he never, in the whole course of his research, thinks of looking for the interference of a supernatural power. In this respect, Biology, as the science of so-called “animated” natural bodies, was formerly placed in sharp opposition to the above-mentioned inorganic natural sciences (Anorganology). It is true modern Physiology, the science of the phenomena of motion in animals and plants, has completely adopted the mechanical view; but Morphology, the science of the forms of animals and plants, has not been affected at all by it. Morphologists, in spite of the position of physiology, have continued, as before, in opposition to the mechanical view of functions, to look upon the forms of animals and plants as something which cannot be at all explained mechanically, but which must owe its origin necessarily to a higher, supernatural creative power, acting for a definite purpose.
In this general view it is quite indifferent whether the creative power be worshipped as a personal god, or whether it be termed the power of life (vis vitalis), or final cause (causa finalis). In any case, to express it in one word, its supporters have recourse to a miracle for an explanation. They throw themselves into the arms of a poetic faith, which as such can have no value in the domain of scientific knowledge.
All that was done before Darwin, to establish a natural mechanical conception of the origin of animals and plants, has been in vain, and until his time no theory gained a general recognition. Darwin’s theory first succeeded in doing this, and thus has rendered an immense service. For the idea of the unity of organic and inorganic nature is now firmly established; and that branch of natural science which had longest and most obstinately opposed mechanical conception and explanation, viz., the science of the structure of animate forms, is launched on to identically the same road towards perfection as that along which all the rest of the natural sciences are travelling. The unity of all natural phenomena is by Darwin’s theory finally established.
This unity of all nature, the animating of all matter, the inseparability of mental power and corporeal substance, Goethe has asserted in the words: “Matter can never exist and be active without mind, nor can mind without matter.” These first principles of the mechanical conception of the universe have been taught by the great monistic philosophers of all ages. Even Democritus of Abdera, the immortal founder of the Atomic theory, clearly expressed them about 500 years before Christ; but the great Dominican friar, Giordano Bruno, did so even more explicitly. For this he was burnt at the stake, by the Christian inquisition in Rome, on the 17th of Feb., 1600, on the same day on which, 36 years before, Galileo, his great fellow-countryman and fellow-worker, was born. Such men, who live and die for a great idea, are usually stigmatized as “materialists”; but their opponents, whose arguments were torture and the stake, are praised as “spiritualists.”
By the Theory of Descent we are for the first time enabled to conceive of the unity of nature in such a manner that a mechanico-causal explanation of even the most intricate organic phenomena, for example, the origin and structure of the organs of sense, is no more difficult (in a general way) than is the mechanical explanation of any physical process; as, for example, earthquakes, the courses of the wind, or the currents of the ocean. We thus arrive at the extremely important conviction that all natural bodies which are known to us are equally animated, that the distinction which has been made between animate and inanimate bodies does not exist. When a stone is thrown into the air, and falls to earth according to definite laws, or when in a solution of salt a crystal is formed, the phenomenon is neither more nor less a mechanical manifestation of life than the growth and flowering of plants, than the propagation of animals or the activity of their senses, than the perception or the formation of thought in man. This final triumph of the monistic conception of nature constitutes the highest and most general merit of the Theory of Descent, as reformed by Darwin.