On purely mechanical and chemical principles Tyndall accounts for the growth from the germ of a tree. The germ would be quiet, but the solar light and heat disturb its dreams, break up its atomic equilibrium. The germ makes an "effort" to restore it (why does it make an effort?), which effort is necessarily defeated and incessantly renewed, and in the turmoil or "sc.r.a.pping" between the germ and the solar forces, matter is gathered from the soil and from the air and built into the special form of a tree. Why not in the form of a cabbage, or a donkey, or a clam? If the forces are purely automatic, why not? Why should matter be gathered in at all in a mechanical struggle between inorganic elements?

But these are not all inorganic; the seed is organic. Ah! that makes the difference! That accounts for the "effort." So we have to have the organic to start with, then the rest is easy. No doubt the molecules of the seed would remain in a quiescent state, if they were not disturbed by external influences, chemical and mechanical. But there is something latent or potential in that seed that is the opposite of the mechanical, namely, the vital, and in what that consists, and where it came from, is the mystery.

III

I fancy that the difficulty which an increasing number of persons find in accepting the mechanistic view of life, or evolution,--the view which Herbert Spencer built into such a ponderous system of philosophy, and which such men as Huxley, Tyndall, Gifford, Haeckel, Verworn, and others, have upheld and ill.u.s.trated,--is temperamental rather than logical. The view is distasteful to a certain type of mind--the flexible, imaginative, artistic, and literary type--the type that loves to see itself reflected in nature or that reads its own thoughts and emotions into nature. In a few eminent examples the two types of mind to which I refer seem more or less blended. Sir Oliver Lodge is a case in point. Sir Oliver is an eminent physicist who in his conception of the totality of things is yet a thoroughgoing idealist and mystic. His solution of the problem of living things is extra-scientific. He sees in life a distinct transcendental principle, not involved in the const.i.tution of matter, but independent of it, entering into it and using it for its own purposes.

Tyndall was another great scientist with an inborn idealistic strain in him. His famous, and to many minds disquieting, declaration, made in his Belfast address over thirty years ago, that in matter itself he saw the promise and the potency of all terrestrial life, stamps him as a scientific materialist. But his conception of matter, as "at bottom essentially mystical and transcendental," stamps him as also an idealist. The idealist in him speaks very eloquently in the pa.s.sage which, in the same address, he puts into the mouth of Bishop Butler, in the latter's imaginary debate with Lucretius: "Your atoms," says the Bishop, "are individually without sensation, much more are they without intelligence. May I ask you, then, to try your hand upon this problem.

Take your dead hydrogen atoms, your dead oxygen atoms, your dead carbon atoms, your dead nitrogen atoms, your dead phosphorus atoms, and all the other atoms, dead as grains of shot, of which the brain is formed.

Imagine them separate and sensationless, observe them running together and forming all imaginable combinations. This, as a purely mechanical process, is _seeable_ by the mind. But can you see or dream, or in any way imagine, how out of that mechanical art, and from these individually dead atoms, sensation, thought, and emotion are to arise? Are you likely to extract Homer out of the rattling of dice, or the Differential Calculus out of the clash of billiard b.a.l.l.s?" Could any vitalist, or Bergsonian idealist have stated his case better?

Now the Bishop Butler type of mind--the visualizing, idealizing, a.n.a.logy-loving, literary, and philosophical mind--is shared by a good many people; it is shared by or is characteristic of all the great poets, artists, seers, idealists of the world; it is the humanistic type that sees man everywhere reflected in nature; and is radically different from the strictly scientific type which dehumanizes nature and reduces it to impersonal laws and forces, which distrusts a.n.a.logy and sentiment and poetry, and clings to a rigid logical method.

This type of mind is bound to have trouble in accepting the physico-chemical theory of the nature and origin of life. It visualizes life, sees it as a distinct force or principle working in and through matter but not of it, super-physical in its origin and psychological in its nature. This is the view Henri Bergson exploits in his "Creative Evolution." This is the view Kant took when he said, "It is quite certain that we cannot even satisfactorily understand, much less explain, the nature of an organism and its internal forces on purely mechanical principles." It is the view Goethe took when he said, "Matter can never exist without spirit, nor spirit without matter."

Tyndall says Goethe was helped by his poetic training in the field of natural history, but hindered as regards the physical and mechanical sciences. "He could not formulate distinct mechanical conceptions; he could not see the force of mechanical reasoning." His literary culture helped him to a literary interpretation of living nature, but not to a scientific explanation of it; it helped put him in sympathy with living things, and just to that extent barred him from the mechanistic conception of those of pure science. Goethe, like every great poet, saw the universe through the colored medium of his imagination, his emotional and aesthetic nature; in short, through his humanism, and not in the white light of the scientific reason. His contributions to literature were of the first order, but his contributions to science have not taken high rank. He was a "prophet of the soul," and not a disciple of the scientific understanding.

If we look upon life as inherent or potential in the const.i.tution of matter, dependent upon outward physical and chemical conditions for its development, we are accounting for life in terms of matter and motion, and are in the ranks of the materialists. But if we find ourselves unable to set the ultimate particles of matter in action, or so working as to produce the reaction which results in life, without conceiving of some new force or principle operating upon them, then we are in the ranks of the vitalists or idealists. The idealists see the original atoms slumbering there in rock and sea and soil for untold ages, till, moved upon by some unknown factor, they draw together in certain fixed order and numbers, and life is the result. Something seems to put a spell upon them and cause them to behave so differently from the way they behaved before they were drawn into the life circuit.

When we think of life, as the materialists do, as of mechanico-chemical origin, or explicable in terms of the natural universal order, we think of the play of material forces amid which we live, we think of their subtle action and interaction all about us--of osmosis, capillarity, radio-activity, electricity, thermism, and the like; we think of the four states of matter,--solid, fluid, gaseous, and ethereal,--of how little our senses take in of their total activities, and we do not feel the need of invoking a transcendental principle to account for it.

Yet to fail to see that what we must call intelligence pervades and is active in all organic nature is to be spiritually blind. But to see it as something foreign to, or separable from, nature is to do violence to our faith in the constancy and sufficiency of the natural order. One star differeth from another star in glory. There are degrees of mystery in the universe. The most mysterious thing in inorganic nature is electricity--that disembodied energy that slumbers in the ultimate particles of matter--unseen, unfelt, unknown, till it suddenly leaps forth with such terrible vividness and power on the face of the storm, or till we summon it through the transformation of some other form of energy. A still higher and more inscrutable mystery is life--that something which clothes itself in such infinitely varied and beautiful as well as unbeautiful forms of matter. We can evoke electricity at will from many different sources, but we can evoke life only from other life; the biogenetic law is inviolable.

IV

It takes some of the cold iron out of the mechanistic theory of life if we divest it of all our a.s.sociations with the machine-mad and machine-ridden world in which we live and out of which our material civilization came. The mechanical, the automatic, is the ant.i.thesis of the spontaneous and the poetic, and it repels us on that account. We are so made that the artificial systems please us far less than the natural systems. A sailing-ship takes us more than a steamship. It is nearer life, nearer the winged creatures. There is determinism in nature, mechanical forces are everywhere operative, but there are no machines in the proper sense of the word. When we call an organism a living machine we at once take it out of the categories of the merely mechanical and automatic and lift it into a higher order--the vital order.

Professor Le Dantec says we are mechanisms in the third degree, a mechanism of a mechanism of a mechanism. The body is a mechanism by virtue of its anatomy--its framework, its levers, its hinges; it is a mechanism by virtue of its chemical activities; and it is a mechanism by virtue of its colloid states--three kinds of mechanisms in one, and all acting together harmoniously and as a unit--in other words, a super-mechanical combination of activities.

The mechanical conception of life repels us because of its a.s.sociation in our minds with the fabrications of our own hands--the dead metal and wood and the noise and dust of our machine-ridden and machine-produced civilization.

But Nature makes no machines like our own. She uses mechanical principles everywhere, in inert matter and in living bodies, but she does not use them in the bald and literal way we do. We must divest her mechanisms of the rigidity and angularity that pertain to the works of our own hands. Her hooks and hinges and springs and sails and coils and aeroplanes, all involve mechanical contrivances, but how differently they impress us from our own application of the same principles! Even in inert matter--in the dews, the rains, the winds, the tides, the snows, the streams,--her mechanics and her chemistry and her hydrostatics and pneumatics, seem much nearer akin to life than our own. We must remember that Nature's machines are not human machines. When we place our machine so that it is driven by the great universal currents,--the wheel in the stream, the sail on the water,--the result is much more pleasing and poetic than when propelled by artificial power. The more machinery we get between ourselves and Nature, the farther off Nature seems. The marvels of crystallization, the beautiful vegetable forms which the frost etches upon the stone flagging of the sidewalk, and upon the window-pane, delight us and we do not reason why. A natural bridge pleases more than one which is the work of an engineer, yet the natural bridge can only stand when it is based upon good engineering principles.

I found at the great Colorado Canon, that the more the monuments of erosion were suggestive of human structures, or engineering and architectural works, the more I was impressed by them. We are pleased when Nature imitates man, and we are pleased when man imitates Nature, and yet we recoil from the thought that life is only applied mechanics and chemistry. But the thought that it is mechanics and chemistry applied by something of which they as such, form no part, some agent or principle which we call vitality, is welcome to us. No machine we have ever made or seen can wind itself up, or has life, no chemical compound from the laboratories ever develops a bit of organic matter, and therefore we are disbelievers in the powers of these things.

V

Is gravity or chemical affinity any more real to the mind than vitality?

Both are names for mysteries. Something which we call life lifts matter up, in opposition to gravity, into thousands of living forms. The tree lifts potash, silica, and lime up one or two hundred feet into the air; it elbows the soil away from its hole where it enters the ground; its roots split rocks. A giant sequoia lifts tons of solid matter and water up hundreds of feet. So will an explosion of powder or dynamite, but the tree does it slowly and silently by the organizing power of life. The vital is as inscrutably identified with the mechanical and chemical as the soul is identified with the body. They are one while yet they are two.

For purely mechanical things we can find equivalents. Arrest a purely mechanical process, and the machine only rests or rusts; arrest a vital process, and the machine evaporates, disintegrates, myriads of other machines reduce it to its original mineral and gaseous elements. In the organic world we strike a principle that is incalculable in its operation and incommensurable in its results. The physico-chemical forces we can bring to book; we know their orbits, their attractions and repulsions, and just what they will and will not do; we can forecast their movements and foresee their effects. But the vital forces transcend all our mathematics; we cannot antic.i.p.ate their behavior.

Start inert matter in motion and we know pretty nearly what will happen to it; mix the chemical elements together and we can foresee the results; but start processes or reactions we call life, and who can foresee the end? We know the sap will mount in the tree and the tree will be true to its type, but what do we or can we know of what it is that determines its kind and size? We know that in certain plants the leaves will always be opposite each other on the stalk, and that in other plants the leaves will alternate; that certain plants will have conspicuous and others inconspicuous flowers; but how can we know what it is in the cells of the plants that determines these things? We can graft the scion of a sour apple tree upon a sweet, and _vice versa_, and the fruit of the scion will be true to its kind, but no a.n.a.lysis of the scion or of the stock will reveal the secret, as it would in the case of chemical compounds. In inorganic nature we meet with concretions, but not secretions; with crystallization, but not with a.s.similation and growth from within. Chemistry tells us that the composition of animal bodies is identical with that of vegetable; that there is nothing in one that is not in the other; and yet, behold the difference! a difference beyond the reach of chemistry to explain. Biology can tell us all about these differences and many other things, but it cannot tell us the secret we are looking for,--what it is that fashions from the same elements two bodies so unlike as a tree and a man.

Decay and disintegration in the inorganic world often lead to the production of beautiful forms. In life the reverse is true; the vital forces build up varied and picturesque forms which when pulled down are shapeless and displeasing. The immense layers of sandstone and limestone out of which the wonderful forms that fill the Grand Canon of the Colorado are carved were laid down in wide uniform sheets; if the waters had deposited their material in the forms which we now see, it would have been a miracle. We marvel and admire as we gaze upon them now; we do more, we have to speculate as to how it was all done by the blind, unintelligent forces. Giant stairways, enormous alcoves, dizzy, highly wrought bal.u.s.trades, ma.s.sive vertical walls standing four-square like huge foundations--how did all the unguided erosive forces do it? The secret is in the structure of the rock, in the lines of cleavage, in the unequal hardness, and in the impulsive, irregular, and unequal action of the eroding agents. These agents follow the lines of least resistance; they are active at different times and seasons, and from different directions; they work with infinite slowness; they undermine, they disintegrate, they dislodge, they transport; the hard streaks resist them, the soft streaks invite them; water charged with sand and gravel saws down; the wind, armed with fine sand, rounds off and hollows out; and thus the sculpturing goes on. But after you have reasoned out all these things, you still marvel at the symmetry and the structural beauty of the forms. They look like the handiwork of barbarian G.o.ds. They are the handiwork of physical forces which we can see and measure and in a degree control. But what a gulf separates them from the handiwork of the organic forces!

VI

Some things come and some things arise; things that already exist may come, but potential things arise; my friend comes to visit me, the tide comes up the river, the cold or hot wave comes from the west; but the seasons, night and morning, health and disease, and the like, do not come in this sense; they arise. Life does not come to dead matter in this sense; it arises. Day and night are not traveling round the earth, though we view them that way; they arise from the turning of the earth upon its axis. If we could keep up with the flying moments,--that is, with the revolution of the earth,--we could live always at sunrise, or sunset, or at noon, or at any other moment we cared to elect. Love or hate does not come to our hearts; it is born there; the breath does not come to the newborn infant; respiration arises there automatically. See how the life of the infant is involved in that first breath, yet it is not its life; the infant must first be alive before it can breathe. If it is still-born, the respiratory reaction does not take place. We can say, then, that the breath means life, and the life means breath; only we must say the latter first. We can say in the same way that organization means life, and life means organization. Something sets up the organizing process in matter. We may take all the physical elements of life known to us and jumble them together and shake them up to all eternity, and life will not result. A little friction between solid bodies begets heat, a little more and we get fire. But no amount of friction begets life. Heat and life go together, but heat is the secondary factor.

Life is always a vanishing-point, a constant becoming--an unstable something that escapes us while we seem to a.n.a.lyze it. In its nature or essence, it is a metaphysical problem, and not one of physical science.

Science cannot grasp it; it evaporates in its crucibles. And science is compelled finally to drive it into an imaginary region--I had almost said, metaphysical region, the region of the invisible, hypothetical atoms of matter. Here in the mysteries of molecular attraction and repulsion, it conceives the secret of life to lie.

"Life is a wave," says Tyndall, but does not one conceive of something, some force or impulse in the wave that is not of the wave? What is it that travels along lifting new water each moment up into waves? It is a physical force communicated usually by the winds. When the wave dies upon the sh.o.r.e, this force is dissipated, not lost, or is turned into heat. Why may we not think of life as a vital force traveling through matter and lifting up into organic life waves in the same way? But not translatable into any other form of energy because not derivable from any other form.

Every species of animal has something about it that is unique and individual and that no chemical or physiological a.n.a.lysis of it will show--probably some mode of motion among its ultimate particles that is peculiar to itself. This prevents cross-breeding among different species and avoids a chaos of animal and vegetable forms. Living tissues and living organs from one species cannot be grafted upon the individuals of another species; the kidney of a cat, for instance, cannot be subst.i.tuted for that of a dog, although the functions and the anatomy of the two are identical. It is suggested that an element of felineness and an element of canineness adhere in the cells of each, and the two are antagonistic. This specific quality, or selfness, of an animal pervades every drop of its blood, so that the blood relationship of the different forms may be thus tested, where chemistry is incompetent to show agreement or antagonism. The reactions of life are surer and more subtle than those of chemistry. Thus the blood relationship between birds and reptiles is clearly shown, as is the relationship of man and the chimpanzee and the orang-outang. The same general fact holds true in the vegetable world. You cannot graft the apple upon the oak, or the plum upon the elm. It seems as if there were the quality of oakness and the quality of appleness, and they would not mix.

The same thing holds among different chemical compounds. Substances which have precisely the same chemical formulae (called isomers) have properties as widely apart as alcohol and ether.

If chemistry is powerless to trace the relationship between different forms of life, is it not highly improbable that the secret of life itself is in the keeping of chemistry?

a.n.a.lytical science has reached the end of its tether when it has resolved a body into its const.i.tuent 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 mult.i.tude 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 a.n.a.lysis. 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 ent.i.ty 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 apt.i.tudes. 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 G.o.ds 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.

Hence the scientific conception of the universe repels many people. They are not equal to it. To think of life as involved in the very const.i.tution of matter itself is a much harder proposition than to conceive of it as Bergson and Sir Oliver Lodge do, as an independent reality. The latter view gives the mind something more tangible to lay hold of. Indeed, science gives the mind nothing to take hold of. Does any chemical process give the mind any separate reality to take hold of?

Is there a spirit of fire, or of decay, or of disease, or of health?

IX

Behold a man with his wonderful body, and still more wonderful mind; try to think of him as being fathered and mothered by the mere mechanical and chemical forces that we see at work in the rocks and soil underfoot, begotten by chemical affinity or the solar energy working as molecular physic, and mothered by the warmth and moisture, by osmosis and the colloid state--and all through the chance clashings and groupings of the irrational physical forces. Nothing is added to them, nothing guides or inspires them, nothing moves upon the face of the waters, nothing breathes upon the insensate clay. The molecules or corpuscles of the four princ.i.p.al elements--carbon, hydrogen, nitrogen, and oxygen--just happened to come together in certain definite numbers, and in a certain definite order, and invented or built up that most marvelous thing in the universe, the cell. The cells put their heads, or bodies, together, and built the tissues, the tissues formed the organs, the organs in convention a.s.sembled organized themselves into the body, and behold! a man, a bird, or a tree!--as chance a happening as the juxtaposition of the grains of sand upon the sh.o.r.e, or the shape of the summer clouds in the sky.

Aristotle dwells upon the internal necessity. The teeth of an animal arise from necessity, he says; the animal must have them in order to live. Yet it must have lived before it had them, else how would the necessity arise? If the horns of an animal arise from the same necessity, the changing conditions of its life begat the necessity; its life problem became more and more complicated, till new tools arose to meet new wants. But without some indwelling principle of development and progress, how could the new wants arise? Spencer says this progress is the result of the action and reaction between organisms and their changing environment. But you must first get your organism before the environment can work its effects, and you must have something in the organism that organizes and reacts from the environment. We see the agents he names astronomic, geologic, meteorologic, having their effects upon inanimate objects as well, but they do not start the process of development in them; they change a stone, but do not transform it into an organism. The chemist can take the living body apart as surely as the watchmaker can take a watch apart, but he cannot put the parts together again so that life will reappear, as the watchmaker can restore the time-keeping power of the watch. The watch is a mere mechanical contrivance with parts fitted to parts externally, while the living body is a mechanical and chemical contrivance, with parts blended with parts internally, so to speak, and acting together through sympathy, and not merely by mechanical adjustment. Do we not have to think of some organizing agent embracing and controlling all the parts, and integral in each of them, making a vital bond instead of a mechanical one?

There are degrees of vitality in living things, whereas there are only degrees of complexity and delicacy and efficiency in mechanical contrivances. One watch differs from another in the perfection of its works, but not as two living bodies with precisely similar structure differ from each other in their hold upon life, or in their measure of vitality. No a.n.a.lysis possible to science could show any difference in the chemistry and physics of two persons of whom one would withstand hardships and diseases that would kill the other, or with whom one would have the gift of long life and the other not. Machines differ from one another quant.i.tatively--more or less efficiency; a living body differs from a machine qualitatively--its efficiency is of a different order; its unity is of a different order; its complexity is of a different order; the interdependence of its parts is of a different order. Yet what a parallel there is between a machine and a living body! Both are run by external forces or agents, solar energy in one applied mechanically from without; in the other applied vitally from within; both suffer from the wear and tear of time and from abuse, but one is self-repaired and the other powerless in this respect--two machines with the same treatment running the same number of years, but two men with the same treatment running a very unequal number of years. Machines of the same kind differ in durability, men differ in powers of endurance; a man can "screw up his courage," but a machine has no courage to screw up. Science may be unable to see any difference between vital mechanics, vital chemistry, and the chemics and mechanics of inorganic bodies--its a.n.a.lysis reveals no difference; but that there is a difference as between two different orders, all men see and feel.