When some three thousand years had passed since his beginning, the unique individual determined to create others of his kind. Not that he suffered from loneliness. Not that he yearned for love, or even for intellectual companionship. But solely for the undertaking of more profound research, he needed the cooperation of beings of his own mental stature. He therefore designed, and had built in various regions of the planet, turrets and factories like his own, though greatly improved. Into each he sent, by his servants, a cell of his own vestigial body, and directed how it should be cultivated so as to produce a new individual. At the same time he caused far-reaching operations to be performed upon himself, so that he should be remade upon a more ample plan. Of the new capacities which he inculcated in himself and his progeny the most important was direct sensitivity to radiation. This was achieved by incorporating in each brain-tissue a specially bred strain of Martian parasites. These henceforth were to live in the great brain as integral members of each one of its cells. Each brain was also equipped with a powerful wireless transmitting apparatus. Thus should the widely scattered sessile population maintain direct ‘telepathic’ contact with one another.

The undertaking was successfully accomplished. Some ten thousand of these new individuals, each specialized for his particular locality and office, now constituted the Fourth Men. On the highest mountains were super-astronomers with vast observatories, whose instruments were partly artificial, partly natural excrescences of their own brains. In the very entrails of the planet others, specially adapted to heat, studied the subterranean forces, and were kept in ‘telepathic’ union with the astronomers. In the tropics, in the Arctic, in the forests, the deserts, and on the ocean floor, the Fourth Men indulged their immense curiosity; and in the homeland, around the father of the race, a group of great buildings housed a hundred individuals. In the service of this world-wide population, those races of Third Men which had originally cooperated to produce the new human species tilled the land, tended the cattle, manufactured the immense material requisites of the new civilization, and satisfied their spirits with an ever more stereotyped ritual of their vital art. This degradation of the whole race to a menial position had occurred slowly, imperceptibly. But the result was none the less irksome. Occasionally there were sparks of rebellion, but they always failed to kindle serious trouble; for the prestige and persuasiveness of the Fourth Men were irresistible.

At length, however, a crisis occurred. For some three thousand years the Fourth Men had pursued their research with constant success, but latterly progress had been slow. It was becoming increasingly difficult to devise new lines of research. True, there was still much detail to be filled in, even in their knowledge of their own planet, and very much in their knowledge of the stars. But there was no prospect of opening up entirely new fields which might throw some light on the essential nature of things. Indeed, it began to dawn on them that they had scarcely plumbed a surface ripple of the ocean of mystery. Their knowledge seemed to them perfectly systematic, yet wholly enigmatic. They had a growing sense that though in a manner they knew almost everything, they really knew nothing.

The normal mind, when it experiences intellectual frustration, can seek recreation in companionship, or physical exercise, or art. But for the Fourth Men there was no such escape. These activities were impossible and meaningless to them. The Great Brains were whole-heartedly interested in the objective world, but solely as a vast stimulus to intellection, never for its own sake. They admired only the intellective process itself and the interpretative formulae and principles which it devised. They cared no more for men and women than for material in a test-tube, no more for one another than for mechanical calculators. Nay, of each one of them it might almost be said that he cared ever for himself solely as an instrument of knowing. Many of the species had actually sacrificed their sanity, even in some cases their lives, to the obsessive lust of intellection.

As the sense of frustration became more and more oppressive, the Fourth Men suffered more and more from the onesidedness of their nature. Though so completely dispassionate while their intellectual life proceeded smoothly, now that it was thwarted they began to be confused by foolish whims and cravings which they disguised from themselves under a cloak of excuses. Sessile and incapable of affection, they continually witnessed the free movement, the group life, the love-making of their menials. Such activities became an offence to them, and filled them with a cold jealousy, which it was altogether beneath their dignity to notice. The affairs of the serf-population began to be conducted by their masters with less than the accustomed justice. Serious grievances arose.

The climax occurred in connexion with a great revival of research, which, it was said, would break down the impalpable barriers and set knowledge in progress again. The Great Brains were to be multiplied a thousandfold, and the resources of the whole planet were to be devoted far more strictly than before to the crusade of intellection. The menial Third Men would therefore have to put up with more work and less pleasure. Formerly they would willingly have accepted this fate for the glory of serving the superhuman brains. But the days of their blind devotion were past. It was murmured among them that the great experiment of their forefathers had proved a great disaster, and that the Fourth Men, the Great Brains, in spite of their devilish cunning, were mere abortions.

Matters came to a head when the tyrants announced that all useless animals must be slaughtered, since their upkeep was too great an economic burden upon the world-community. The vital art, moreover, was to be practised in future only by the Great Brains themselves. This announcement threw the Third Men into violent excitement, and divided them into two parties. Many of those whose lives were spent in direct service of the Great Brains favoured implicit obedience, though even these were deeply distressed. The majority, on the other hand, absolutely refused to permit the impious slaughter, or even to surrender their privileges as vital artists. For, they said, to kill off the fauna of the planet would be to violate the fair form of the universe by blotting out many of its most beautiful features. It would be an outrage to the Life God, and he would surely avenge it. They therefore urged that the time was come for all true human beings to stand together and depose the tyrants. And this, they pointed out, could easily be done. It was only necessary to cut a few electric cables, connecting the Great Brains with the subterranean generating stations. The electric pumps would then cease to supply the brain-turrets with aerated blood. Or, in the few cases in which the Great Brains were so located that they could control their own source of power in wind or water, it was necessary merely to refrain from transporting food to their digestion laboratories.

The personal attendants of the Great Brains shrank from such action; for their whole lives had been devoted, proudly and even in a manner lovingly, to service of the revered beings. But the agriculturists determined to withhold supplies. The Great Brains, therefore, armed their servitors with a diversity of ingenious weapons. Immense destruction was done; but since the rebels were decimated, there were not enough hands to work the fields. Some of the Great Brains, and many of their servants, actually died of starvation. And as hardship increased, the servants themselves began to drift over to the rebels. It now seemed certain to the Third Men that the Great Brains would very soon be impotent, and the plant once more under the control of natural beings. But the tyrants were not to be so easily defeated. Already for some centuries they had been secretly experimenting with a means of gaining a far more thorough dominion over the natural species. At the eleventh hour they succeeded.

In this undertaking they had been favoured by the results which a section of the natural species itself had produced long ago in the effort to breed specialized communicants to keep in touch with the unseen world. That sect, or theocratic nation, which had striven for many centuries toward this goal, had finally attained what they regarded as success. There came into existence an hereditary caste of communicants. Now, though these beings were subject to mediumistic trances in which they apparently conversed with denizens of the other world and received instructions about the ordering of matters terrestrial, they were in fact merely abnormally suggestible. Trained from childhood in the lore of the unseen world, their minds, during the trance, were amazingly fertile in developing fantasies based on that lore. Left to themselves, they were merely folk who were abnormally lacking in initiative and intelligence. Indeed, so naïve were they, and so sluggish, that they were mentally more like cattle than human beings. Yet under the influence of suggestion they became both intelligent and vigorous. Their intelligence, however, operating strictly in service of the suggestion, was wholly incapable of criticizing the suggestion itself.

There is no need to revert to the downfall of this theocratic society, beyond saying that, since both private and public affairs were regulated by reference to the sayings of the communicants, inevitably the state fell into chaos. The other community of the Third Men, that which was engaged upon breeding the Great Brains, gradually dominated the whole planet. The mediumistic stock, however, remained in existence, and was treated with a half-contemptuous reverence. The mediums were still generally regarded as in some manner specially gifted with the divine spirit, but they were now thought to be too holy for their sayings to have any relation to mundane affairs.

It was by means of this mediumistic stock that the Great Brains had intended to consolidate their position. Their earlier efforts may be passed over. But in the end they produced a race of living and even intelligent machines whose will they could control absolutely, even at a great distance. For the new variety of Third Men was ‘telepathically’ united with its masters. Martian units had been incorporated in its nervous system.

At the last moment the Great Brains were able to put into the field an army of these perfect slaves, which they equipped with the most efficient lethal weapons. The remnant of original servants discovered too late that they had been helping to produce their supplanters. They joined the rebels, only to share in the general destruction. In a few months all the Third Men, save the new docile variety, were destroyed; except for a few specimens which were preserved in cages for experimental purposes. And in a few years every type of animal that was not known to be directly or indirectly necessary to human life had been exterminated. None were preserved even as specimens, for the Great Brains had already studied them through and through.

But though the Great Brains were now absolute possessors of the Earth, they were after all no nearer their goal than before. The actual struggle with the natural species had provided them with an aim; but now that the struggle was over, they began to be obsessed once more with their intellectual failure. With painful clarity they realized that, in spite of their vast weight of neural tissue, in spite of their immense knowledge and cunning, they were practically no nearer the ultimate truth than their predecessors had been. Both were infinitely far from it.

For the Fourth Men, the Great Brains, there was no possible life but the life of intellect; and the life of intellect had become barren. Evidently something more than mere bulk of brain was needed for the solving of the deeper intellectual problems. They must, therefore, somehow create a new brain-quality, or organic formation of brain, capable of a mode of vision or insight impossible in their present state. They must learn somehow to remake their own brain-tissues upon a new plan. With this aim, and partly through unwitting jealousy of the natural and more balanced species which had created them, they began to use their captive specimens of that species for a great new enterprise of research into the nature of human brain-tissue. It was hoped thus to find some hint of the direction in which the new evolutionary leap should take place. The unfortunate specimens were therefore submitted to a thousand ingenious physiological and psychological tortures. Some were kept alive with their brains spread out permanently on a laboratory table, for microscopic observation during their diverse psychological reactions. Others were put into fantastic states of mental abnormality. Others were maintained in perfect health of body and mind, only to be felled at last by some ingeniously contrived tragic experience. New types were produced which, it was hoped, might show evidence of emergence into a qualitatively higher mode of mentality; but in fact they succeeded only in ranging through the whole gamut of insanity.

The research continued for some thousands of years, but gradually slackened, so utterly barren did it prove to be. As this frustration became more and more evident, a change began to come over the minds of the Fourth Men.

They knew, of course, that the natural species valued many things and activities which they themselves did not appreciate at all. Hitherto this had seemed a symptom merely of the low mental development of the natural species. But the behaviour of the unfortunate specimens upon whom they had been experimenting had gradually given the Fourth Men a greater insight into the likings and admirations of the natural species, so that they had learned to distinguish between those desires which were fundamental and those merely accidental cravings which clear thinking would have dismissed. In fact, they came to see that certain activities and certain objects were appreciated by these beings with the same clear-sighted conviction as they themselves appreciated knowledge. For instance, the natural human beings valued one another, and were sometimes capable of sacrificing themselves for the sake of others. They also valued love itself. And again they valued very seriously their artistic activities; and the activities of their bodies and of animal bodies appeared to them to have intrinsic excellence.

Little by little the Fourth Men began to realize that what was wrong with themselves was not merely their intellectual limitation, but, far more seriously, the limitation of their insight into values. And this weakness, they saw, was the result, not of paucity of intellective brain, but of paucity of body and lower brain tissues. This defect they could not remedy. It was obviously impossible to remake themselves so radically that they should become of a more normal type. Should they concentrate their efforts upon the production of new individuals more harmonious than themselves? Such a work, it might be supposed, would have seemed unattractive to them. But no. They argued thus. ‘It is our nature to care most for knowing. Full knowledge is to be attained only by minds both more penetrating and more broadly based than ours. Let us, therefore, waste no more time in seeking to achieve the goal in ourselves. Let us seek rather to produce a kind of being, free from our limitations, in whom we may attain the goal of perfect knowledge vicariously. The producing of such a being will exercise all our powers, and will afford the highest kind of fulfilment possible to us. To refrain from this work would be irrational.’

Thus it came about that the artificial Fourth Men began to work in a new spirit upon the surviving specimens of the Third Men to produce their own supplanters.