Another trouble now occurred. Several electrolysis stations on Venus were wrecked, apparently by submarine eruption. Also, a number of ether-ships, engaged in surveying the ocean, mysteriously exploded. The explanation was found when one of these vessels, though damaged, was able to return to the earth. The commander reported that, when the sounding line was drawn up, a large spherical object was seen to be attached to it. Closer inspection showed that this object was fastened to the sounding apparatus by a hook, and was indeed unmistakably artificial, a structure of small metal plates riveted together. While preparations were being made to bring the object within the ship, it happened to bump against the hull, and then it exploded.

Evidently there must be intelligent life somewhere in the ocean of Venus. Evidently the marine Venerians resented the steady depletion of their aqueous world, and were determined to stop it. The terrestrials had assumed that water in which no free oxygen was dissolved could not support life. But observation soon revealed that in this world-wide ocean there were many living species, some sessile, others free-swimming, some microscopic, others as large as whales. The basis of life in these creatures lay not in photosynthesis and chemical combination, but in the controlled disintegration of radio-active atoms. Venus was particularly rich in these atoms, and still contained certain elements which had long ago ceased to exist on the earth. The oceanic fauna subsisted in the destruction of minute quantities of radio-active atoms throughout its tissues.

Several of the Venerian species had attained considerable mastery over their physical environment, and were able to destroy one another very competently with various mechanical contrivances. Many types were indeed definitely intelligent and versatile within certain limits. And of these intelligent types, one had come to dominate all the others by virtue of its superior intelligence, and had constructed a genuine civilization on the basis of radio-active power. These most developed of all the Venerian creatures were beings of about the size and shape of a swordfish. They had three manipulative organs, normally sheathed within the long ‘sword’, but capable of extension beyond its point, as three branched muscular tentacles. They swam with a curious screw-like motion of their bodies and triple tails. Three fins enabled them to steer. They had also organs of phosphorescence, vision, touch, and something analogous to hearing. They appeared to reproduce asexually, laying eggs in the ooze of the ocean bed. They had no need of nutrition in the ordinary sense; but in infancy they seemed to gather enough radio-active matter to keep them alive for many years. Each individual, when his stock was running out and he began to be feeble, was either destroyed by his juniors or buried in a radio-active mine, to rise from this living death in a few months completely rejuvenated.

At the bottom of the Venerian ocean these creatures thronged in cities of proliferated coral-like buildings, equipped with many complex articles, which must have constituted the necessities and luxuries of their civilization. So much was ascertained by the Terrestrials in the course of their submarine exploration. But the mental life of the Venerians remained hidden. It was clear, indeed, that like all living things, they were concerned with self-maintenance and the exercise of their capacities; but of the nature of these capacities little was discoverable. Clearly they used some kind of symbolic language, based on mechanical vibrations set up in the water by the snapping claws of their tentacles. But their more complex activities were quite unintelligible. All that could be recorded with certainty was that they were much addicted to warfare, even to warfare between groups of one species; and that even in the stress of military disaster they maintained a feverish production of material articles of all sorts, which they proceeded to destroy and neglect.

One activity was observed which was peculiarly mysterious. At certain seasons three individuals, suddenly developing unusual luminosity, would approach one another with rhythmic swayings and tremors, and would then rise on their tails and press their bodies together. Sometimes at this stage an excited crowd would collect, whirling around the three like driven snow. The chief performers would now furiously tear one another to pieces with their crab-like pincers, till nothing was left but tangled shreds of flesh, the great swords, and the still twitching claws. The Terrestrials, observing these matters with difficulty, at first suspected some kind of sexual intercourse; but no reproduction was ever traced to this source. Possibly the behaviour had once served a biological end, and had now become a useless ritual. Possibly it was a kind of voluntary religious sacrifice. More probably it was of a quite different nature, unintelligible to the human mind.

As man’s activities on Venus became more extensive, the Venerians became more energetic in seeking to destroy him. They could not come out of the ocean to grapple with him, for they were deep-sea organisms. Deprived of oceanic pressure, they would have burst. But they contrived to hurl high explosives into the centres of the islands, or to undermine them from tunnels. The work of electrolysis was thus very seriously hampered. And as all efforts to parley with the Venerians failed completely, it was impossible to effect a compromise. The Fifth Men were thus faced with a grave moral problem. What right had man to interfere in a world already possessed by beings who were obviously intelligent, even though their mental life was incomprehensible to man? Long ago man himself had suffered at the hands of Martian invaders, who doubtless regarded themselves as more noble than the human race. And now man was committing a similar crime. On the other hand, either the migration to Venus must go forward, or humanity must be destroyed; for it seemed quite certain by now that the moon would fall, and at no very distant date. And though man’s understanding of the Venerians was so incomplete, what he did know of them strongly suggested that they were definitely inferior to himself in mental range. This judgement might, of course, be mistaken; the Venerians might after all be so superior to man that man could not get an inkling of their superiority. But this argument would apply equally to jelly-fish and micro-organisms. Judgement had to be passed according to the evidence available. So far as man could judge at all in the matter, he was definitely the higher type.

There was another fact to be taken into account. The life of the Venerian organism depended on the existence of radio-active atoms. Since those atoms are subject to disintegration, they must become rarer. Venus was far better supplied than the earth in this respect, but there must inevitably come a time when there would be no more radio-active matter in Venus. Now submarine research showed that the Venerian fauna had once been much more extensive, and that the increasing difficulty of procuring radio-active matter was already the great limiting factor of civilization. Thus the Venerians were doomed, and man would merely hasten their destruction.

It was hoped, of course, that in colonizing Venus mankind would be able to accommodate itself without seriously interfering with the native population. But this proved impossible for two reasons. In the first place, the natives seemed determined to destroy the invader even if they should destroy themselves in the process. Titanic explosions were engineered, which caused the invaders serious damage, but also strewed the ocean surface with thousands of dead Venerians. Secondly, it was found that, as electrolysis poured more and more free oxygen into the atmosphere, the ocean absorbed some of the potent element back into itself by solution; and this dissolved oxygen had a disastrous effect upon the oceanic organisms. Their tissues began to oxidize. They were burnt up, internally and externally, by a slow fire. Man dared not stop the process of electrolysis until the atmosphere had become as rich in oxygen as his native air. Long before this state was reached, it was already clear that the Venerians were beginning to feel the effects of the poison, and that in a few thousand years, at most, they would be exterminated. It was therefore determined to put them out of their misery as quickly as possible. Men could by now walk abroad on the islands of Venus, and indeed the first settlements were already being founded. They were thus able to build a fleet of powerful submarine vessels to scour the ocean and destroy the whole native fauna.

This vast slaughter influenced the mind of the fifth human species in two opposite directions, now flinging it into despair, now rousing it to grave elation. For on the one hand the horror of the slaughter produced a haunting guiltiness in all men’s minds, an unreasoning disgust with humanity for having been driven to murder in order to save itself. And this guiltiness combined with the purely intellectual loss of self-confidence which had been produced by the failure of science to account for the moon’s approach. It reawakened, also, that other quite irrational sense of guilt which had been bred of sympathy with the everlasting distress of the past. Together, these three influences tended toward racial neurosis.

On the other hand a very different mood sometimes sprang from the same three sources. After all, the failure of science was a challenge to be gladly accepted; it opened up a wealth of possibilities hitherto unimagined. Even the unalterable distress of the past constituted a challenge; for in some strange manner the present and future, it was said, must transfigure the past. As for the murder of Venerian life, it was, indeed, terrible, but right. It had been committed without hate; indeed, rather in love. For as the navy proceeded with its relentless work, it had gathered much insight into the life of the natives, and had learned to admire, even in a sense to love, while it killed. This mood, of inexorable yet not ruthless will, intensified the spiritual sensibility of the species, refined, so to speak, its spiritual hearing, and revealed to it tones and themes in the universal music which were hitherto obscure.

Which of these two moods, despair or courage, would triumph? All depended on the skill of the species to maintain a high degree of vitality in untoward circumstances.

Man now busied himself in preparing his new home. Many kinds of plant life, derived from the terrestrial stock, but bred for the Venerian environment, now began to swarm on the islands and in the sea. For so restricted was the land surface, that great areas of ocean had to be given over to specially designed marine plants, which now formed immense floating continents of vegetable matter. On the least torrid islands appeared habitable pylons, forming an architectural forest, with vegetation on every acre of free ground. Even so, it would be impossible for Venus ever to support the huge population of the earth. Steps had therefore been taken to ensure that the birth-rate should fall far short of the death-rate; so that, when the time should come, the race might emigrate without leaving any living members behind. No more than a hundred million, it was reckoned, could live tolerably on Venus. The population had therefore to be reduced to a hundredth of its former size. And since, in the terrestrial community, with its vast social and cultural activity, every individual had fulfilled some definite function in society, it was obvious that the new community must be not merely small but mentally impoverished. Hitherto, each individual had been enriched by intercourse with a far more intricate and diverse social environment that would be possible on Venus.

Such was the prospect when at length it was judged advisable to leave the earth to its fate. The moon was now so huge that it periodically turned day into night, and night into a ghastly day. Prodigious tides and distressful weather conditions had already spoilt the amenities of the earth, and done great damage to the fabric of civilization. And so at length humanity reluctantly took flight. Some centuries passed before the migration was completed, before Venus had received, not only the whole remaining human population, but also representatives of many other species of organisms, and all the most precious treasure of man’s culture.