Our concern is with humanity, and with the Martians only in relation to men. But in order to understand the tragic intercourse of the two planets, it is necessary to glance at conditions on Mars, and conceive something of those fantastically different yet fundamentally similar beings, who were now seeking to possess man’s home.

To describe the biology, psychology, and history of a whole world in a few pages is as difficult as it would be to give the Martians themselves in the same compass a true idea of man. Encyclopaedias, libraries, would be needed in either case. Yet, somehow, I must contrive to suggest the alien sufferings and delights, and the many aeons of struggle, which went to the making of these strange non-human intelligences, in some ways so inferior yet in others definitely superior to the human species which they encountered.

Mars was a world whose mass was about one-tenth that of the earth. Gravity therefore had played a less tyrannical part in Martian than in terrestrial history. The weakness of Martian gravity combined with the paucity of the planet’s air envelope to make the general atmospheric pressure far lighter than on earth. Oxygen was far less plentiful. Water also was comparatively rare. There were no oceans or seas, but only shallow lakes and marshes, many of which dried up in summer. The climate of the planet was in general very dry, and yet very cold. Being without cloud, it was perennially bright with the feeble rays of a distant sun.

Earlier in the history of Mars, when there were more air, more water, and a higher temperature from internal heat, life had appeared in the coastal waters of the seas, and evolution had proceeded in much the same manner as on earth. Primitive life was differentiated into the fundamental animal and vegetable types. Multicellular structures appeared, and specialized themselves in diverse manners to suit diverse environments. A great variety of plant forms clothed the lands, often with forests of gigantic and slender-stemmed plumes. Mollusc-like and insect-like animals crept or swam, or shot themselves hither and thither in fantastic jumps. Huge spidery creatures of a type not wholly unlike crustaceans, or gigantic grasshoppers, bounded after their prey, and developed a versatility and cunning which enabled them to dominate the planet almost as, at a much later date, early man was to dominate the terrestrial wild.

But meanwhile a rapid loss of atmosphere, and especially of water-vapour, was changing Martian conditions beyond the limits of adaptability of this early fauna and flora. At the same time a very different kind of vital organization was beginning to profit by the change. On Mars, as on the Earth, life had arisen from one of many ‘subvital’ forms. The new type of life on Mars evolved from another of these subvital kinds of molecular organization, one which had hitherto failed to evolve at all, and had played an insignificant part, save occasionally as a rare virus in the respiratory organs of animals. These fundamental subvital units of organization were ultra-microscopic, and indeed far smaller than the terrestrial bacteria, or even the terrestrial viruses. They originally occurred in the marshy ponds, which dried up every spring, and became depressions of baked mud and dust. Certain of their species, borne into the air upon dust-particles, developed an extremely dry habit of life. They maintained themselves by absorbing chemicals from the wind-borne dust, and a very slight amount of moisture from the air. Also they absorbed sunlight by a photosynthesis almost identical with that of the plants.

To this extent they were similar to the other living things, but they had also certain capacities which the other stock had lost at the very outset of its evolutionary career. Terrestrial organisms, and Martian organisms of the terrestrial type, maintained themselves as vital unities by means of nervous systems, or other forms of material contact between parts. In the most developed forms, an immensely complicated neural ‘telephone’ system connected every part of the body with a vast central exchange, the brain. Thus on the earth a single organism was without exception a continuous system of matter, which maintained a certain constancy of form. But from the distinctively Martian subvital unit there evolved at length a very different kind of complex organism, in which material contact of parts was not necessary either to coordination of behaviour or unity of consciousness. These ends were achieved upon a very different physical basis. The ultra-microscopic subvital members were sensitive to all kinds of ethereal vibrations, directly sensitive, in a manner impossible to terrestrial life; and they could also initiate vibrations. Upon this basis Martian life developed at length the capacity of maintaining vital organization as a single conscious individual without continuity of living matter. Thus the typical Martian organism was a cloudlet, a group of free-moving members dominated by a ‘group-mind’. But in one species individuality came to inhere, for certain purposes, not in distinct cloudlets only, but in a great fluid system of cloudlets. Such was the single-minded Martian host which invaded the Earth.

The Martian organism depended, so to speak, not on ‘telephone’ wires, but on an immense crowd of mobile ‘wireless stations’, transmitting and receiving different wave-lengths according to their function. The radiation of a single unit was of course very feeble; but a great system of units could maintain contact with its wandering parts over a considerable distance.

One other important characteristic distinguished the dominant form of life on Mars. Just as a cell, in the terrestrial form of life, has often the power of altering its shape (whence the whole mechanism of muscular activity), so in the Martian form the free-floating ultra-microscopic unit might be specialized for generating around itself a magnetic field, and so either repelling or attracting its neighbours. Thus a system of materially disconnected units had a certain cohesion. Its consistency was something between a smoke-cloud and a very tenuous jelly. It had a definite though ever-changing contour and resistant surface. By massed mutual repulsions of its constituent units it could exercise pressure on surrounding objects; and in its most concentrated form the Martian cloud-jelly could bring to bear immense forces which could also be controlled for very delicate manipulation. Magnetic forces were also responsible for the mollusc-like motion of the cloud as a whole over the ground, and again for the transport of lifeless material and living units from region to region within the cloud.

The magnetic field of repulsion and attraction generated by a subvital unit was much more restricted than its field of ‘wireless’ communication. Similarly with organized systems of units. Thus each of the cloudlets which the Second Men saw in their sky was an independent motor unit; but also it was in a kind of ‘telepathic’ communication with all its fellows. Indeed in every public enterprise, such as the terrestrial campaigns, almost perfect unity of consciousness was maintained within the limits of a huge field of radiation. Yet only when the whole population concentrated itself into a small and relatively dense cloud-jelly, did it become a single magnetic motor unit. The Martians, it should be noted, had three possible forms, or formations, namely: first, an ‘open order’ of independent and very tenuous cloudlets in ‘telepathic’ communication, and often in strict unity as a group-mind; second, a more concentrated and less vulnerable corporate cloud; and third, an extremely concentrated and formidable cloud-jelly.

Save for these very remarkable characteristics, there was no really fundamental difference between the distinctively Martian and the distinctively terrestrial forms of life. The chemical basis of the former was somewhat more complicated than that of the latter; and selenium played a part in it, to which nothing corresponded in terrestrial life. The Martian organism, moreover, was unique in that it fulfilled within itself the functions of both animal and vegetable. But, save for these peculiarities, the two types of life were biochemically much the same. Both needed material from the ground, both needed sunlight. Each lived in the chemical changes occurring in its own ‘flesh’. Each, of course, tended to maintain itself as an organic unity. There was a certain difference, indeed, in respect of reproduction; for the Martian subvital units retained the power of growth and subdivision. Thus the birth of a Martian cloud arose from the subdivision of myriads of units within the parent cloud, followed by their ejection as a new individual. And, as the units were highly specialized for different functions, representatives of many types had to pass into the new cloud.

In the earliest stages of evolution on Mars the units had become independent of each other as soon as they parted in reproduction. But later the hitherto useless and rudimentary power of emitting radiation was specialized, so that, after reproduction, free individuals came to maintain radiant contact with one another, and to behave with ever-increasing coordination. Still later, these organized groups themselves maintained radiant contact with groups of their offspring, thus constituting larger individuals with specialized members. With each advance in complexity the sphere of radiant influence increased; until, at the zenith of Martian evolution, the whole planet (save for the remaining animal and vegetable representatives of the other and unsuccessful kind of life) constituted sometimes a single biological and psychological individual. But this occurred as a rule only in respect of matters which concerned the species as a whole. At most times the Martian individual was a cloudlet, such as those which first astonished the Second Men. But in great public crises each cloudlet would suddenly wake up to find himself the mind of the whole race, sensing through many individuals, and interpreting his sensations in the light of the experience of the whole race.

The life which dominated Mars was thus something between an extremely well-disciplined army of specialized units, and a body possessed by one mind. Like an army, it could take any form without destroying its organic unity. Like an army it was sometimes a crowd of free-wandering units, yet at other times also it disposed itself in very special orders to fulfil special functions. Like an army it was composed of free, experiencing individuals who voluntarily submitted themselves to discipline. On the other hand, unlike an army, it woke occasionally into unified consciousness.

The same fluctuation between individuality and multiplicity which characterized the race as a whole, characterized also each of the cloudlets themselves. Each was sometimes an individual, sometimes a swarm of more primitive individuals. But while the race rather seldom rose to full individuality, the cloudlets declined from it only in very special circumstances. Each cloudlet was an organization of specialized groups formed of minor specialized groups, which in turn were composed of the fundamental specialized varieties of subvital units. Each free-roving group of free-roving units constituted a special organ, fulfilling some particular function in the whole. Thus some were specialized for attraction and repulsion, some for chemical operations, some for storing the sun’s energy, some for emitting radiation, some for absorbing and storing water, some for special sensitivities, such as awareness of mechanical pressure and vibration, or temperature changes, or light rays. Others again were specialized to fulfil the function of the brain of man; but in a peculiar manner. The whole volume of the cloudlet vibrated with innumerable ‘wireless’ messages in very many wave-lengths from the different ‘organs’. It was the function of the ‘brain’ units to receive, and correlate, and interpret these messages in the light of past experience, and to initiate responses in the wave-lengths appropriate to the organs concerned.

All these subvital units, save a few types that were too highly specialized, were capable of independent life as air-borne bacteria or viruses. And whenever they lost touch with the radiation of the whole system, they continued to live their own simple lives until they were once more controlled. All were free-floating units, but normally they were under the influence of the cloudlet’s system of electro-magnetic fields, and were directed hither and thither for their special functions. And under this influence some of them might be held rigidly in position in relation to one another. Such was the case of the organs of sight. In early stages of evolution, some of the units had specialized for carrying minute globules of water. Later, much larger droplets were carried, millions of units holding between them a still microscopic globule of life’s most precious fluid. Ultimately this function was turned to good account in vision. Aqueous lenses as large as the eye of an ox were supported by a scaffolding of units; while, at focal length from the lens, a rigid retina of units was held in position. Thus the Martian could produce eyes of every variety whenever he wanted them, and telescopes and microscopes too. This production and manipulation of visual organs was of course largely subconscious, like the focusing mechanism in man. But latterly the Martians had greatly increased their conscious control of physiological processes; and it was this achievement which facilitated their remarkable optical triumphs.

One other physiological function we must note before considering the Martian psychology. The fully evolved, but as yet uncivilized, Martian had long ago ceased to depend for his chemicals on wind-borne volcanic dust. Instead, he rested at night on the ground, like a knee-high mist on terrestrial meadows, and projected specialized tubular groups of units into the soil, like rootlets. Part of the day also had to be occupied in this manner. Somewhat later this process was supplemented by devouring the declining plant-life of the planet. But the final civilized Martians had greatly improved their methods of exploiting the ground and the sunlight, both by mechanical means and by artificial specialization of their own organs. Even so, however, as their activities increased, these vegetable functions became an ever more serious problem for them. They practised agriculture; but only a very small area of the arid planet could be induced to bear. It was terrestrial water and terrestrial vegetation that finally determined them to make the great voyage.