It is a daring prophecy, but every probability of Science attests the likelihood of its fulfilment. The goal looked forward to from the beginning of time has been attained. Nature has succeeded in making a Man; she can go no further; Organic Evolution has done its work.
This is not a conceit of Science, nor a reminiscence of the pre-Copernican idea that the centre of the universe is the world, and the centre of the world Man. It is the sober scientific probability that with the body of Man the final fruit of the tree of Organic Evolution has appeared; that the highest possibilities open to flesh and bone and nerve and muscle have now been realized; that in whatever direction, and with whatever materials, Evolution still may work, it will never produce any material thing more perfect in design or workmanship; that in Man, in short, about this time in history, we are confronted with a stupendous crisis in Nature, -- the Arrest of the Animal. The Man, the Animal Man, the Man of Organic Evolution, it is at least certain, will not go on. It is another Man who will go on, a Man within this Man; and that he may go on the first Man must stop. Let us try for a moment to learn what it is to stop. Nothing could teach Man better what is meant by his going on.
One of the most perfect pieces of mechanism in the human body is the Hand. How long it has taken to develop may be dimly seen by a glance at the long array of less accurate instruments of prehension which shade away with ever decreasing delicacy and perfectness as we descend the scale of animal life. At the bottom of that scale is the Amoeba. It is a speck of protoplasmic jelly, headless, footless, and armless. When it wishes to seize the microscopic particle of food on which it lives a portion of its body lengthens out, and, moving towards the object, flows over it, engulfs it, and melts back again into the body. This is its Hand. At any place, and at any moment, it creates a Hand. Each Hand is extemporized as it is needed; when not needed it is not. Pass a little higher up the scale and observe the Sea-Anemone. The Hand is no longer extemporized as occasion requires, but lengthened portions of the body are set apart and kept permanently in shape for the purpose of seizing food. Here, in the capital of twining tentacles which crowns the quivering pillar of the body, we get the rude approximation to the most useful portion of the human Hand -- the separated fingers. It is a vast improvement on the earlier Hand, but the jointless digits are still imperfect; it is simply the Amoeba Hand cut into permanent strips.
Passing over a multitude of intermediate forms, watch, in the next place, the Hand of an African Monkey. Note the great increase in usefulness due to the muscular arm upon which the Hand is now extended, and the extraordinary capacity for varied motion afforded by the three-fold system of jointing at shoulder, elbow, and wrist. The Hand itself is almost the human Hand; there are palm and nail and articulated fingers. But observe how one circumstance hinders the possessor from taking full advantage of these great improvements, -- this Hand has no thumb, or if it has, it is but a rudiment. To estimate the importance of this apparently insignificant organ, try for a moment without using the thumb to hold a book, or write a letter, or do any single piece of manual work. A thumb is not merely an additional finger, but a finger so arranged as to be opposable to the other fingers, and thus possesses a practical efficacy greater than all the fingers put together. It is this which gives the organ the power to seize, to hold, to manipulate, to do higher work; this simple mechanical device in short endows the Hand of intelligence with all its capacity and skill. Now there are animals, like the Colobi, which have no thumb at all; there are others, like the Marmoset, which possess the thumb, but in which it is not opposable; and there are others, the Chimpanzee for instance, in which the Hand is in all essentials identical with Man's. In the human form the thumb is a little longer, and the whole member more delicate and shapely, but even for the use of her highest product, Nature has not been able to make anything much more perfect than the hand of this anthropoid ape.
Is the Hand then finished? Can Nature take out no new patent in this direction? Is the fact that no novelty is introduced in the case of Man a proof that the ultimate Hand has appeared? By no means. And yet it is probable for other reasons that the ultimate Hand has appeared; that there will never be a more perfectly handed animal than Man. And why? Because the causes which up to this point have furthered the evolution of the Hand have begun to cease to act. In the perfecting of the bodily organs, as of all other mechanical devices, necessity is the mother of invention. As the Hand was given more and more to do, it became more and more adapted to its work. Up to a point, it responded directly to each new duty that was laid upon it. But only up to a point. There came a time when the necessities became too numerous and too varied for adaptation to keep pace with them. And the fatal day came, the fatal day for the Hand, when he who bore it made a new discovery. It was the discovery of Tools. Henceforth what the Hand used to do, and was slowly becoming adapted to do better, was to be done by external appliances. So that if anything new arose to be done, or to be better done, it was not a better Hand that was now made but a better tool. Tools are external Hands. Levers are the extensions of the bones of the arm. Hammers are callous substitutes for the fist. Knives do the work of nails. The vice and the pincers replace the fingers. The day that Cave-man first split the marrow bone of a bear by thrusting a stick into it, and striking it home with a stone -- that day the doom of the Hand was sealed.
But has not Man to make his tools, and will not that induce the development of the Hand to an as yet unknown perfection? No. Because tools are not made with the Hand. They are made with the Brain. For a time, certainly, Man had to make his tools, and for a time this work recompensed him physically, and the arm became elastic and the fingers dexterous and strong. But soon he made tools to make these tools. In place of shaping things with the Hand, he invented the turning-lathe; to save his fingers he requisitioned the loom; instead of working his muscles he gave out the contract to electricity and steam. Man, therefore, from this time forward will cease to develop materially these organs of his body. If he develops them outside his body, filling the world everywhere with artificial Hands, supplying the workshops with fingers more intricate and deft than Organic Evolution could make in a millennium, and loosing energies upon them infinitely more gigantic than his muscles could generate in a life-time, it is enough. Evolution after all is a slow process. Its great labour is to work up to a point where Invention shall be possible, and where, by the powers of the human mind, and by the mechanical utilization of the energies of the universe, the results of ages of development may be anticipated. Further changes, therefore, within the body itself are made unnecessary. Evolution has taken a new departure. For the Arrest of the Hand is not the cessation of Evolution but its immense acceleration, and the re-direction of its energies into higher channels.
Take up the functions of the animal body one by one, and it will be seen how the same arresting finger is laid upon them all. To select an additional illustration, consider the power of Sight. Without pausing to trace the steps by which the Eye has reached its marvellous perfection, or to estimate the ages spent in polishing its lenses and adjusting the diaphragms and screws, ask the simple question whether, under the conditions of modern civilization, anything now is being added to its quickening efficiency, or range. Is it not rather the testimony of experience that if anything its power has begun to wane? Europe even now affords the spectacle of at least one nation so short-sighted that it might almost be called a myopic race. The same causes, in fact, that led to the Arrest of the Hand are steadily working to stop the development of the Eye. Man, when he sees with difficulty, does not now improve his Eye; he puts on a pince-nez. Spectacles -- external eyes -- have superseded the work of Evolution. When his sight is perfect up to a point, and he desires to examine objects so minute as to lie beyond the limit of that point, he will not wait for Evolution to catch up upon his demand and supply him, or his children's children, with a more perfect instrument. He will invest in a microscope. Or when he wishes to extend his gaze to the moon and stars, he does not hope to reach to-morrow the distances which to-day transcend him. He invents the telescope. Organic Evolution has not even a chance. In every direction the external eye has replaced the internal, and it is even difficult to suggest where any further development of this part of the animal can now come in. There are still, and in spite of all instruments, regions in which the unaided organs of Man may continue to find a field for the fullest exercise, but the area is slowly narrowing, and in every direction the appliances of Science tempt the body to accept those supplements of the Arts, which, being accepted, involve the discontinuance of development for all the parts concerned. Even where a mechanical appliance, while adding range to a bodily sense, has seemed to open a door for further improvement, some correlated discovery in a distant field of science, as by some remorseless fate, has suddenly taken away the opportunity and offered to the body only an additional inducement for neglect. Thus it might be thought that the continuous use of the telescope, in the attempt to discover more and more indistinct and distant heavenly bodies, might tend to increase the efficiency of the Eye. But that expectation has vanished already before a further fruit of Man's inventive power. By an automatic photographic apparatus fixed to the telescope, an Eye is now created vastly more delicate and in many respects more efficient than the keenest eye of Man. In at least five important particulars the Photographic Eye is the superior of the Eye of Organic Evolution. It can see where the human Eye, even with the best aids of optical instruments, sees nothing at all; it can distinguish certain objects with far greater clearness and definition; owing to the rapidity of its action it can instantly detect changes which are too sudden for the human eye to follow; it can look steadily for hours without growing tired; and it can record what it sees with infallible accuracy upon a plate which time will not efface. How long would it take Organic Evolution to arrive at an Eye of such amazing quality and power? And with such a piece of mechanism available, who, rather than employ it even to the neglect of his organs of vision, would be content to await the possible attainment of an equal perfection by his descendants some million years hence? Is there not here a conspicuous testimony to the improbability of a further Evolution of the sense of Sight in civilized communities -- in other words, another proof of the Arrest of the Animal? What defiance of Evolution, indeed, what affront to Nature, is this? Man prepares a complicated telescope to supplement the Eye created by Evolution, and no sooner is it perfected than it occurs to him to create another instrument to aid the Eye in what little work is left for it to do. That is to say, he first makes a mechanical supplement to his Eye, then constructs a mechanical Eye, which is better than his own, to see through it, and ends by discarding, for many purposes, the Eye of Organic Evolution altogether.
As regards the other functions of civilized Man, the animal in almost every direction has reached its maximum. Civilization -- and the civilized state, be it remembered, is the ultimate goal of every race and nation -- is always attended by deterioration of some of the senses. Every man pays a definite price or forfeit for his taming. The sense of smell, compared with its development among the lower animals, is in civilized Man already all but gone. Compared even with a savage, it is an ascertained fact that the civilized Man in this respect is vastly inferior. So far as hearing is concerned, the main stimulus -- fear of surprise by enemies -- has ceased to operate, and the muscles for the erection of the ears have fallen into disuse. The ear itself in contrast with that of the savage is slow and dull, while compared with the quick sense of the lower animals, the organ is almost deaf. The skin, from the continuous use of clothes, has forfeited its protective power. Owing to the use of viands cooked, the muscles of the jaw are rapidly losing strength. The teeth, partly for a similar reason, are undergoing marked degeneration. The third molar, for instance, among some nations is already showing symptoms of suppression, and that this threatens ultimate extinction may be reasoned from the fact that the anthropoid apes have fewer teeth than the lower monkeys, and these fewer than the preceding generation of insectivorous mammals.
In an age of vehicles and locomotives the lower limbs find their occupation almost gone. For mere muscle, that on which his whole life once depended, Man has almost now no use. Agility, nimbleness, strength, once a stern necessity, are either a luxury or a pastime. Their outlet is the cricket-field or the tennis-court. To keep them up at all, artificial means -- dumb-bells, parallel-bars, clubs -- have actually to be devised. Vigour of limb is not to be found in common life, we look for it in the Gymnasium; agility is relegated to the Hippodrome. Once all men were athletes; now you have to pay to see them. More or less with all the animal powers it is the same. To some extent at least some phonograph may yet speak for us, some telephone hear for us, the typewriter write for us, chemistry digest for us, and incubation nurture us. So everywhere the Man as Animal is in danger of losing ground. He has expanded until the world is his body. The former body, the hundred and fifty pounds or so of organized tissue he carries about with him, is little more than a mark of identity. It is not he who is there, he cannot be there, or anywhere, for he is everywhere. The material part of him is reduced to a symbol; it is but a link with the wider framework of the Arts, a belt between machinery and machinery. His body no longer generates, but only utilizes energy; alone he is but a tool, a medium, a turncock of the physical forces.
Now with what feelings do we regard all this? Is not the crowning proof of the thesis under review that we watch this evidence accumulating against the body with no emotion and hear the doom of our clay pronounced without a regret? It is nothing to aspiring Man to watch the lower animals still perfecting their mechanism and putting all his physical powers and senses to the shame. It is nothing to him to be distanced in nimbleness by the deer: has he not his bullet? Or in strength by the horse: has he not bit and bridle? Or in vision by the eagle: his field-glass out-sees it. How easily we talk of the body as a thing without us, as an impersonal it And how naturally when all is over, do we advertise its irrelevancy to ourselves by consigning its borrowed atoms to the anonymous dust. The fact is, in one aspect, the body, to Intelligence, is all but an absurdity. One is almost ashamed to have one. The idea of having to feed it, and exercise it, and humour it, and put it away in the dark to sleep, to carry it about with one everywhere, and not only it but its wardrobe -- other material things to make this material thing warm or keep it cool -- the whole situation is a comedy. But judge what it would be if this exacting organism went on evolving, multiplied its members, added to its intricacy, waxed instead of waned? So complicated is it already that one shrinks from contemplating a future race having to keep in repair an apparatus more involved and delicate. The practical advantage is enormous of having all improvements henceforth external, of having insensate organs made of iron and steel rather than of wasting muscle and palpitating nerve. For these can be kept at no physiological cost, they cannot impede the other machinery, and when that finally comes to the last break-down there will be the fewer wheels to stop.
So great indeed is the advantage of increasing mechanical supplements to the physical frame rather than exercising the physical frame itself, that this will become nothing short of a temptation; and not the least anxious task of future civilization will be to prevent degeneration beyond a legitimate point, and keep up the body to its highest working level. For the first thing to be learned from these facts is not that the Body is nothing and must now decay, but that it is most of all and more than ever worthy to be preserved. The moment our care of it slackens, the Body asserts itself. It comes out from under arrest -- which is the one thing to be avoided. Its true place by the ordained appointment of Nature is where it can be ignored; if through disease, neglect, or injury it returns to consciousness the effect of Evolution is undone. Sickness is degeneration; pain the signal to resume the evolution. On the one hand, one must "reckon the Body dead"; on the other, one must think of it in order not to think of it.
This arrest of physical development at a specific point is not confined to Man. Everywhere in the organic world science is confronted with arrested types. While endless groups of plant and animal forms have advanced during the geological ages, other whole groups have apparently stood still -- stood still, that is to say, not in time but in organization. If Nature is full of moving things, it is also full of fixtures. Thirty-one years ago Mr. Huxley devoted the anniversary Address of the Geological Society to a consideration of what he called "Persistent Types of Life," and threw down to Evolutionists a puzzle which has never yet been fully solved. While some forms attained their climacteric tens of thousands of years ago and perished, others persevered, and, without advancing in any material respect, are alive to this day. Among the most ancient Carboniferous plants, for instance, are found certain forms generically identical with those now living. The cone of the existing Araucaria is scarcely to be distinguished from that of an Oolite form. The Tabulate Corals of the Silurian period are similar to those which exist to-day. The Lamp-shells of our present seas so abounded at the same ancient date as to give their name to one of the great groups of Silurian rocks -- the Lingula Flags. Star-fishes and urchins, almost the same as those which tenant the coast-lines of our present seas, crawled along what are now among the most ancient fossiliferous rocks. Both of the forms just named, the Brachiopods and the Echinoderms, have come down to us almost unchanged through the nameless gap of time which separates the Silurian and Old Red Sandstone periods from the present era.
This constancy of structure reveals a conservatism in Nature, as unexpected as it is widespread. Does it mean that the architecture of living things has a limit beyond which development cannot go? Does it mean that the morphological possibilities along certain lines of bodily structure have exhausted themselves, that the course of conceivable development in these instances has actually run out? In Gothic Architecture, or in Norman, there are terminal points which, once reached, can be but little improved upon. Without limiting working efficiency, they can go no further. These styles in the very nature of things seem to have limits. Mr. Ruskin has indeed assured us that there are only three possible forms of good architecture in the world; Greek, the architecture of the Lintel; Romanesque, the architecture of the Rounded Arch; Gothic, the architecture of the Gable. "All the architects in the world will never discover any other way of bridging a space than these three, the Lintel, the Round Arch, the Gable; they may vary the curve of the arch, or curve the sides of the gable, or break them down; but in doing this they are merely modifying or sub-dividing, not adding to the generic form." 
In some such way, there may be terminal generic forms in the architecture of animals; and the persistent types just named may represent in their several directions the natural limits of possible modification. No further modification of a radical kind, that is to say, could in these instances be introduced without detriment to practical efficiency. These terminal forms thus mark a normal maturity, a goal; they represent the ends of the twigs of the tree of life.
Now consider the significance of that fact. Nature is not an interminable succession. It is not always a becoming. Sometimes things arrive. The Lamp-shells have arrived, they are part of the permanent furniture of the world; along that particular line, there will probably never be anything higher. The Star-fishes also have arrived, and the Sea-urchins, and the Nautilus, and the Bony Fishes, the Tapirs, and possibly the Horse -- all these are highly divergent forms which have run out the length of their tether and can go no further. When the plan of the world was made, to speak teleologically, these types of life were assigned their place and limit, and there they have remained. If it were wanted to convey the impression that Nature had some large end in view, that she was not drifting aimlessly towards a general higher level, it could not have been done more impressively than by everywhere placing on the field of Science these fixed points, these innumerable consummations, these clean-cut mountain peaks, which for millenniums have never grown. Even as there is a plan in the parts, there is a plan in the whole.
But the most certain of all these "terminal points" in the evolution of Creation is the body of Man. Anatomy places Man at the head of all other animals that were ever made; but what is infinitely more instructive, with him, as we have just seen, the series comes to an end. Man is not only the highest branch, but the highest possible branch Take as a last witness the testimony of anatomy itself with regard to the human brain. Here the fact is not only re-affirmed but the rationale of it suggested in terms of scientific law. "The development of the brain is in connection with a whole system of development of the head and face which cannot be carried further than in Man. For the mode in which the cranial cavity is gradually increased in size is a regular one, which may be explained thus: we may look on the skull as an irregular cylinder, and at the same time that it is expanded by increase of height and width it also undergoes a curvature or bending on itself, so that the base is crumpled together while the roof is elongated. This curving has gone on in Man till the fore end of the cylinder, the part on which the brain rests above the nose, is nearly parallel to the aperture of communication of the skull with the spinal canal, i.e. the cranium has a curve of 180deg. or a few degrees more or less. This curving of the base of the skull involves change in position of the face bones also, and could not go on to a further extent without cutting off the nasal cavity from the throat. . . . Thus there is anatomical evidence that the development of the vertebrate form has reached its limit by completion in Man." 
This author's conception of the whole field of living nature is so suggestive that we may continue the quotation: "To me the animal kingdom appears not in indefinite growth like a tree, but a temple with many minarets, none of them capable of being prolonged -- while the central dome is completed by the structure of man. The development of the animal kingdom is the development of intelligence chained to matter; the animals in which the nervous system has reached the greatest perfection are the vertebrates, and in Man that part of the nervous system which is the organ of intelligence reaches, as I have sought to show, the highest development possible to a vertebrate animal, while intelligence has grown to reflection and volition. On these grounds, I believe, not that Man is the highest possible intelligence, but that the human body is the highest form of human life possible, subject to the conditions of matter on the surface of the globe, and that the structure completes the design of the animal kingdom." 
Never was the body of Man greater than with this sentence of suspension passed on it, and never was Evolution more wonderful or more beneficent than when the signal was given to stop working at Man's animal frame. This was an era in the world's history. For it betokened nothing less than that the cycle of matter was now complete, and the one prefatory task of the ages finished. Henceforth the Weltanschauung is for ever changed. From this pinnacle of matter is seen at last what matter is for, and all the lower lives that ever lived appear as but the scaffolding for this final work. The whole sub-human universe finds its reason for existence in its last creation, its final justification in the new immaterial order which opened with its close. Cut off Man from Nature, and, metaphysical necessity apart, there remains in Nature no divinity. To include Man in Evolution is not to lower Man to the level of Nature, but to raise Nature to his high estate. There he was made, these atoms are his confederates, these plant cells raised him from the dust, these travailing animals furthered his Ascent: shall he excommunicate them now that their work is done? Plant and animal have each their end, but Man is the end of all the ends. The latest science reinstates him, where poet and philosopher had already placed him, as at once the crown, the master, and the rationale of creation. "Not merely," says Kant, "is he like all organized beings an end in nature, but also here on earth the last end of nature, in reference to whom all other natural things constitute a system of ends." Yet it is not because he is the end of ends, but the beginning of beginnings, that the completion of the Body marks a crisis in the past. At last Evolution had culminated in a creation so complex and exalted as to form the foundation for an inconceivably loftier super-organic order. The moment an organism was reached through which Thought was possible, nothing more was required of matter. The Body was high enough. Organic Evolution might now even resign its sovereignty of the world; it had made a thing which was now its master. Henceforth Man should take charge of Evolution even as up till now he had been the one charge of it. Henceforth his selection should replace Natural Selection; his judgment guide the struggle for life; his will determine for every plant upon the earth whether it should bloom or fade, for every animal whether it should increase, or change, or die. So Man entered into his Kingdom.
Science is charged, be it once more recalled, with numbering Man among the beasts, and levelling his body with the dust. But he who reads for himself the history of creation as it is written by the hand of Evolution will be overwhelmed by the glory and honour heaped upon this creature. To be a Man, and to have no conceivable successor; to be the fruit and crown of the long past eternity, and the highest possible fruit and crown; to be the last victor among the decimated phalanxes of earlier existences, and to be nevermore defeated; to be the best that Nature in her strength and opulence can produce; to be the first of that new order of beings who by their dominion over the lower world and their equipment for a higher, reveal that they are made in the Image of God -- to be this is to be elevated to a rank in Nature more exalted than any philosophy or any poetry or any theology have ever given to Man. Man was always told that his place was high; the reason for it he never knew till now; he never knew that his title deeds were the very laws of Nature, that he alone was the Alpha and Omega of Creation, the beginning and the end of Matter, the final goal of Life.
Nature is full of new departures; but never since time began was there anything approaching in importance that period when the slumbering animal, Brain, broke into intelligence, and the Creature first felt that it had a Mind. From that dateless moment a higher and swifter progress of the world began. Henceforth, Intelligence triumphed over structural adaptation. The wise were naturally selected before the strong. The Mind discovered better methods, safer measures, shorter cuts. So the body learned to refer to it, then to defer to it. As the Mind was given more to do, it enlarged and did its work more perfectly. Gradually the favours of Evolution -- exercise, alteration, differentiation, addition -- which were formerly distributed promiscuously among the bodily organs -- were now lavished mainly upon the Brain. The gains accumulated with accelerating velocity; and by sheer superiority and fitness for its work, the Intellect rose to commanding power, and entered into final possession of a monopoly which can never be disturbed.
Now this means not only that an order of higher animals has appeared upon the earth, but that an altogether new page in the history of the universe has begun to be written. It means nothing less than that the working of Evolution has changed its course. Once it was a physical universe, now it is a psychical universe. And to say that the working of Evolution has changed its course, and set its compass in psychical directions, is to call attention to the most remarkable fact in Nature. Nothing so original or so revolutionary has ever been given to science to discover, to ponder, or to proclaim. The power of this event to strike and rouse the mind will depend upon one's sense of what the working of Evolution has been to the world; but those who realize this even dimly will see that no emphasis of language can exaggerate its significance. Let imagination do its best to summon up the past of Nature. Beginning with the panorama of the Nebular Hypothesis, run the eye over the field of Palaeontology, Geology, Botany, and Zoology. Watch the majestic drama of Creation unfolding, scene by scene and act by act. Realize that one power, and only one, has marshalled the figures for this mighty spectacle; that one hand, and only one, has carried out these transformations; that one principle, and only one, has controlled each subsidiary plot and circumstance; that the same great patient unobtrusive law has guided and shaped the whole from its beginnings in bewilderment and chaos to its end in order, harmony, and beauty. Then watch the curtain drop. And as it moves to rise again, behold the new actor upon the stage. Silently, as all great changes come, Mental Evolution has succeeded Organic. All the things that have been now lie in the far background as forgotten properties. And Man stands alone in the foreground, and a new thing, Spirit, strives within him.
 Fiske, Destiny of Man, p. 26. What follows owes much to this suggestive brochure.  Stones of Venice, II. 236.  Prof J. Cleland, M.D., F.R.S., Journal of Anatomy, Vol. XVIII., pp. 360-1.  Journal of Anatomy, Vol. XVIII., p. 362.
 Stones of Venice, II. 236.
 Prof J. Cleland, M.D., F.R.S., Journal of Anatomy, Vol. XVIII., pp. 360-1.
 Journal of Anatomy, Vol. XVIII., p. 362.