Man’s sojourn on Venus lasted somewhat longer than his whole career on the Earth. From the days of Pithecanthropus to the final evacuation of his native planet he passed, as we have seen, through a bewildering diversity of form and circumstance. On Venus, though the human type was somewhat more constant biologically, it was scarcely less variegated in culture.

To give an account of this period, even on the minute scale that has been adopted hitherto, would entail another volume. I can only sketch its bare outline. The sapling, humanity, transplanted into foreign soil, withers at first almost to the root, slowly readjusts itself, grows into strength and a certain permanence of form, burgeons, season by season, with leaf and flower of many successive civilizations and cultures, sleeps winter by winter, through many ages of reduced vitality, but at length (to force the metaphor), avoids this recurrent defeat by attaining an evergreen constitution and a continuous efflorescence. Then once more, through the whim of Fate, it is plucked up by the roots and cast upon another world.

The first human settlers on Venus knew well that life would be a sorry business. They had done their best to alter the planet to suit human nature, but they could not make Venus into another Earth. The land surface was minute. The climate was almost unendurable. The extreme difference of temperature between the protracted day and night produced incredible storms, rain like a thousand contiguous waterfalls, terrifying electrical disturbances, and fogs in which a man could not see his own feet. To make matters worse, the oxygen supply was as yet barely enough to render the air breathable. Worse still, the liberated hydrogen was not always successfully ejected from the atmosphere. It would sometimes mingle with the air to form an explosive mixture, and sooner or later there would occur a vast atmospheric flash. Recurrent disasters of this sort destroyed the architecture and the human inhabitants of many islands, and further reduced the oxygen supply. In time, however, the increasing vegetation made it possible to put an end to the dangerous process of electrolysis.

Meanwhile, these atmospheric explosions crippled the race so seriously that it was unable to cope with a more mysterious trouble which beset it some time after the migration. A new and inexplicable decay of the digestive organs, which first occurred as a rare disease, threatened within a few centuries to destroy mankind. The physical effects of this plague were scarcely more disastrous than the psychological effects of the complete failure to master it; for, what with the mystery of the moon’s vagaries and the deep-seated, unreasoning sense of guilt produced by the extermination of the Venerians, man’s self-confidence was already seriously shaken, and his highly organized mentality began to show symptoms of derangement. The new plague was, indeed, finally traced to something in the Venerian water, and was supposed to be due to certain molecular groupings, formerly rare, but subsequently fostered by the presence of terrestrial organic matter in the ocean. No cure was discovered.

And now another plague seized upon the enfeebled race. Human tissues had never perfectly assimilated the Martian units which were the means of ‘telepathic’ communication. The universal ill-health now favoured a kind of ‘cancer’ of the nervous system, which was due to the ungoverned proliferation of these units. The harrowing results of this disease may be left unmentioned. Century by century it increased; and even those who did not actually contract the sickness lived in constant terror of madness.

These troubles were aggravated by the devastating heat. The hope that, as the generations passed, human nature would adapt itself even to the more sultry regions, seemed to be unfounded. Far otherwise, within a thousand years the once-populous arctic and antarctic islands were almost deserted. Out of each hundred of the great pylons, scarcely more than two were inhabited, and these only by a few plague-stricken and broken-spirited human relics. These alone were left to turn their telescopes upon the earth and watch the unexpectedly delayed bombardment of their native world by the fragments of the moon.

Population decreased still further. Each brief generation was slightly less well developed than its parents. Intelligence declined. Education became superficial and restricted. Contact with the past was no longer possible. Art lost its significance, and philosophy its dominion over the minds of men. Even applied science began to be too difficult. Unskilled control of the subatomic sources of power led to a number of disasters, which finally gave rise to a superstition that all ‘tampering with nature’ was wicked, and all the ancient wisdom a snare of Man’s Enemy. Books, instruments, all the treasures of human culture, were therefore burnt. Only the perdurable buildings resisted destruction. Of the incomparable world-order of the Fifth Men nothing was left but a few island tribes cut off from one another by the ocean, and from the rest of space-time by the depths of their own ignorance.

After many thousands of years human nature did begin to adapt itself to the climate and to the poisoned water without which life was impossible. At the same time a new variety of the fifth species now began to appear, in which the Martian units were not included. Thus at last the race regained a certain mental stability, at the expense of its faculty of ‘telepathy’, which man was not to regain until almost the last phase of his career. Meanwhile, though he had recovered somewhat from the effects of an alien world, the glory that had been was no more. Let us therefore hurry through the ages that passed before noteworthy events again occurred.

In early days on Venus men had gathered their foodstuff from the great floating islands of vegetable matter which had been artificially produced before the migration. But as the oceans became populous with modifications of the terrestrial fauna, the human tribes turned more and more to fishing. Under the influence of its marine environment, one branch of the species assumed such an aquatic habit that in time it actually began to develop biological adaptations for marine life. It is perhaps surprising that man was still capable of spontaneous variation; but the fifth human species was artificial, and had always been prone to epidemics of mutation. After some millions of years of variation and selection there appeared a very successful species of seal-like submen. The whole body was moulded to stream-lines. The lung capacity was greatly developed. The spine had elongated, and increased in flexibility. The legs were shrunken, grown together, and flattened into a horizontal rudder. The arms also were diminutive and fin-like, though they still retained the manipulative forefinger and thumb. The head had sunk into the body and looked forward in the direction of swimming. Strong carnivorous teeth, emphatic gregariousness, and a new, almost human, cunning in the chase, combined, to make these seal-men lords of the ocean. And so they remained for many million years, until a more human race, annoyed at their piscatorial successes, harpooned them out of existence.

For another branch of the degenerated fifth species had retained a more terrestrial habit and the ancient human form. Sadly reduced in stature and in brain, these abject beings were so unlike the original invaders that they are rightly considered a new species, and may therefore be called the Sixth Men. Age after age they gained a precarious livelihood by grubbing roots upon the forest-clad islands, trapping the innumerable birds, and catching fish in the tidal inlets with ground bait. Not infrequently they devoured, or were devoured by, their seal-like relatives. So restricted and constant was the environment of these human remnants, that they remained biologically and culturally stagnant for some millions of years.

At length, however, geological events afforded man’s nature once more the opportunity of change. A mighty warping of the planet’s crust produced an island almost as large as Australia. In time this was peopled, and from the clash of tribes a new and versatile race emerged. Once more there was methodical tillage, craftsmanship, complex social organization, and adventure in the realm of thought.

During the next two hundred million years all the main phases of man’s life on earth were many times repeated on Venus with characteristic differences. Theocratic empires; free and intellectualistic island cities; insecure overlordships of feudal archipelagos; rivalries of high priest and emperor; religious feuds over the interpretation of sacred scriptures; recurrent fluctuations of thought from naïve animism, through polytheism, conflicting monotheisms, and all the desperate ‘isms’ by which mind seeks to blur the severe outline of truth; recurrent fashions of comfort-seeking fantasy and cold intelligence; social disorders through the misuse of volcanic or wind-power in industry; business empires and pseudo-communistic empires—all these forms flitted over the changing substance of mankind again and again, as in an enduring hearth-fire there appear and vanish the infinitely diverse forms of flame and smoke. But all the while the brief spirits, in whose massed configurations these forms inhered, were intent chiefly on the primitive needs of food, shelter, companionship, crowd-lust, love-making, the two-edged relationship of parent and child, the exercise of muscle and intelligence in facile sport. Very seldom, only in rare moments of clarity, only after ages of misapprehension, did a few of them, here and there, now and again, begin to have the deeper insight into the world’s nature and man’s. And no sooner had this precious insight begun to propagate itself, than it would be blotted out by some small or great disaster, by epidemic disease, by the spontaneous disruption of society, by an access of racial imbecility, by a prolonged bombardment of meteorites, or by the mere cowardice and vertigo that dared not look down the precipice of the fact.