Analytical science has reached the end of its tether when it has resolved a body into its constituent elements. Why or how these elements build up a man in the one case, and a monkey in another, is beyond its province to say. It can deal with all the elements of the living body, vegetable and animal; it can take them apart and isolate them in different bottles; but it cannot put them together again as they were in life. It knows that the human body is built up of a vast multitude of minute cells, that these cells build tissues, that the tissues build organs, that the organs build the body; but the secret of the man, or the dog, or even the flea, is beyond its reach. The secret of biology, that which makes its laws and processes differ so widely from those of geology or astronomy, is a profound mystery. Science can take living tissue and make it grow outside of the body from which it came, but it will only repeat endlessly the first step of life—that of cell-multiplication; it is like a fire that will burn as long as fuel is given it and the ashes are removed; but it is entirely purposeless; it will not build up the organ of which it once formed a part, much less the whole organized body.
The difference between one man and another does not reside in his anatomy or physiology, or in the elements of which the brains and bodies are composed, but in something entirely beyond the reach of experimental science to disclose. The difference is psychological, or, we may say, philosophical, and science is none the wiser for it. The mechanics and the chemistry of a machine are quite sufficient to account for it, plus the man behind it. To the physics and chemistry of a living body, we are compelled to add some intangible, unknowable principle or tendency that physics and chemistry cannot disclose or define. One hesitates to make such a statement lest he do violence to that oneness, that sameness, that pervades the universe.
All trees go to the same soil for their ponderable elements, their ashes, and to the air and the light for their imponderable,—their carbon and their energy,—but what makes the tree, and makes one tree differ from another? Has the career of life upon this globe, the unfolding of the evolutionary process, been accounted for when you have named all the physical and material elements and processes which it involves? We take refuge in the phrase "the nature of things," but the nature of things evidently embraces something not dreamed of in our science.
VII
It is reported that a French scientist has discovered the secret of the glow-worm's light. Of course it is a chemical reaction,—what else could it be?—but it is a chemical reaction in a vital process. Our mental and spiritual life—our emotions of art, poetry, religion—are inseparable from physical processes in the brain and the nervous system; but is that their final explanation? The sunlight has little effect on a withered leaf, but see what effect it has upon the green leaf upon the tree! The sunlight is the same, but it falls upon a new force or potency in the chlorophyll of the leaf,—a bit of chemistry there inspired by life,—and the heat of the sun is stored up in the carbon or woody tissues of the plant or tree, to be given out again in our stoves or fireplaces. And behold how much more of the solar heat is stored up in one kind of a tree than in certain other kinds,—how much in the hickory, oak, maple, and how little comparatively in the pine, spruce, linden,—all through the magic of something in the leaf, or shall we say of the spirit of the tree? If the laws of matter and force alone account for the living organism, if we do not have to think of something that organizes, then how do we account for the marvelous diversity of living forms, and their still more marvelous power of adaptation to changed conditions, since the laws of matter and force are the same everywhere? Science can deal only with the mechanism and chemistry of life, not with its essence; that which sets up the new activity in matter that we call vital is beyond its analysis. It is hard to believe that we have told the whole truth about a living body when we have enumerated all its chemical and mechanical activities. It is by such enumeration that we describe a watch, or a steam-engine, or any other piece of machinery. Describe I say, but such description does not account for the watch or tell us its full significance. To do this, we must include the watchmaker, and the world of mind and ideas amid which he lives. Now, in a living machine, the machine and the maker are one. The watch is perpetually self-wound and self-regulated and self-repaired. It is made up of millions of other little watches, the cells, all working together for one common end and ticking out the seconds and minutes of life with unfailing regularity. Unlike the watch we carry in our pockets, if we take it apart so as to stop its ticking, it can never be put together again. It has not merely stopped; it is dead.
The late William Keith Brooks, of Johns Hopkins University, said in opposition to Huxley that he held to the "old-fashioned conviction that living things do in some way, and in some degree, control or condition inorganic nature; that they hold their own by setting the mechanical properties of matter in opposition to each other, and that this is their most notable and distinctive characteristic." And yet, he said, to think of the living world as "anything but natural" is impossible.
VIII
Life seems to beget a new kind of chemistry, the same elements behave so differently when they are drawn into the life circuit from what they did before. Carbon, for instance, enters into hundreds of new compounds in the organic world that are unknown in the inorganic world. I am thus speaking of life as if it were something, some force or agent, that antedates its material manifestations, whereas in the eyes of science there is no separation of the one from the other. In an explosion there is usually something anterior to, or apart from, the explosive compound, that pulls the trigger, or touches the match, or completes the circuit, but in the slow and gentle explosions that keep the life machinery going, we cannot make such a distinction. The spark and the powder are one; the gun primes and fires itself; the battery is perpetually self-charged; the lamp is self-trimmed and self-lit.
Sir Oliver Lodge is apparently so impressed with some such considerations that he spiritualizes life, and makes it some mysterious entity in itself, existing apart from the matter which it animates and uses; not a source of energy but a timer and releaser of energy. Henri Bergson, in his "Creative Evolution," expounds a similar philosophy of life. Life is a current in opposition to matter which it enters into, and organizes into the myriads of living forms.
I confess that it is easier for me to think of life in these terms than in terms of physical science. The view falls in better with our anthropomorphic tendencies. It appeals to the imagination and to our myth-making aptitudes. It gives a dramatic interest to the question. With Bergson we see life struggling with matter, seeking to overcome its obduracy, compromising with it, taking a half-loaf when it cannot get a whole one; we see evolution as the unfolding of a vast drama acted upon the stage of geologic time. Creation becomes a perpetual process, the creative energy an ever-present and familiar fact. Bergson's book is a wonderful addition to the literature of science and of philosophy. The poet, the dreamer, the mystic, in each of us takes heart at Bergson's beautiful philosophy; it seems like a part of life; it goes so well with living things. As James said, it is like the light of the morning and the singing of birds; we glory in seeing the intellect humbled as he humbles it. The concepts of science try our mettle. They do not appeal to our humanity, or to our myth-making tendencies; they appeal to the purely intellectual, impersonal force within us. Though all our gods totter and fall, science goes its way; though our hearts are chilled and our lives are orphaned, science cannot turn aside, or veil its light. It does not temper the wind to the shorn lamb.