"By the same reasoning then, I suppose the intelligent beings, or what we call men, will be great giants twenty-five feet high?" I put in.

"Some have thought so, but I do not at all agree with them," replied the doctor. "I stick to the theory of small men for small planets, and large men for large planets. There is no possible reason for a large man on Mars, where muscular development is uncalled for and useless, and where the inhabitable space is small. If there are men on Jupiter, they must of necessity be enormously strong to hold themselves up and resist gravitation. If they walk upright (which I think unlikely), their legs must be very large and as solid as iron. The Martian legs are likely to be small and puny, and I believe the upper limbs will be much more strongly developed. In fact, on Mars the Creator had His one great opportunity of making a flying man, and I do not think He has overlooked it. With a rather small, tightly-knit frame, and the upper limbs developed into wings as long as the body, flying against the weak Martian gravitation would be perfectly easy, and a vast advantage over walking."

"Ah! then perhaps they will fly out to meet you!" I ejaculated.

"If they do, they will be stricken with fear to see that we fly without wings and so much more rapidly," he answered, and continued: "If a flying race has been created there, we shall probably find the atmosphere deeper and relatively (though not actually) denser than the Earth's. This would serve to add buoyancy and still further diminish weight, thus making flying quite natural and simple. I certainly do not believe that the Martians are subjected to the tedium of walking. If they do not fly, they will at least make long, swift, graceful hops or jumps of some ten or fifteen feet each. This would require a more hinged development of the lower limbs, like a bird's. It is also possible that the lower limbs may have the prehensile function, and do all the handling and working."

"But how about intelligence and intellectual development? That is the main thing, after all," said I.

"To answer that takes one into the realm of pure speculation. There are but few facts to guide one's guesses. But the trip yonder is worth making, if only to learn that. I do not incline to the opinion that their civilization is vastly older and more developed than ours. Granting the nebular theory of the origin of the universe (which is, after all, only a guess), it is not even then certain that Mars was thrown off the central sun before the Earth. It is much smaller, and may have been thrown off later and travelled farther for this reason. Another good reason for believing in a less advanced civilization is the length of the Martian year and consequent sluggishness of the seasons. He requires 687 of our days to complete his sun revolution, making his years nearly twice as long as ours. I believe his whole development is at a correspondingly slow rate of speed."

"Which do you think is the most advanced and enlightened planet, then?" I ventured.

"That one which finds a way to visit the others first," he answered, with a touch of pride.

"But there may be a tinge of personal conceit in that idea," I suggested.

"Possibly a mere tinge, but the essence of it is apparent truth," he declared. "That planet which has learned the most, made the greatest discoveries and the most useful inventions, is the best and fittest teacher of the others, and will be the sharpest and keenest to gather new information and formulate new science. It is eminently fit that representatives of such a planet should visit the others, and eminently unfit that any primitive civilization engaged in base wars and striving for mere conquest should be allowed that privilege. An all-wise Creator would not permit a huge, strong, ignorant race entirely to overrun and extinguish one weaker but more intelligent. He might permit a strong, intelligent, masterful race to rule and direct a weaker and dependent one, as a schoolmaster rules and guides a child."

"Then you think we are the wise and masterful race?"

"As no other race has yet discovered us; as they have all left the Space Problem unsolved, and as it has been uncovered to us, that is my irresistible conclusion."

"Still, you will not go with ideas of conquest, but to teach and to learn?"

"We shall take with us swords, shields, and fire-arms, for defence. Unless I mistake the nature of their metals, our steel will resist any weapon they can manufacture. But what explosives or what noxious gases they may have, all strange to us, it is impossible to conjecture. Therefore, we shall go with peace in our hands."

"What progress do you think they have made in inventions?" I suggested, as the doctor hesitated.

"If they are winged men, I should say they have never felt that urgent need of railroads, steam boats, telegraphs and telephones, which was the mother of their invention here. Flying or air-travelling machines will no more have occurred to them than a walking machine to us. They will have thoroughly explored every part of their planet, and it is possible that their cities will have been built on high plateaus, or even on mountain peaks. But they will not have builded greatly, for they will have been able to use the great architecture of nature in a way impossible to us."

"Have you heard the theory advanced by some humorous scientist not long ago, that the organs of locomotion and prehension would some day, or on some planet, be supplanted by machinery, and that digestive apparatus would give way for artificially prepared blood?" I asked.

"Oh, yes, that fanciful idea is novel, but irrational. It makes man only a fraction of a being. On every planet, no matter what the advancement of civilization, we shall find complete beings, not dependent on adventitious machinery for locomotion or labour, or on artificial or animal blood for nutriment. Think how helpless such a creature would be at the loss or rusting of his machinery, and at the exhaustion of just the right sort of nutritive fluid. Our digestive apparatus will convert a thousand different foods into blood. Suppose we could live only on buffalo meat? We should all have been dead long ago. We might as well imagine men as mere fungus brains, swimming in rivers of blood; or as beings beyond the necessity of personal thought, and living on brain sandwiches, cut from the thinking heads of others. Eating is not only a necessity, but a pleasure——"

"That is just what I was thinking," I interposed, looking at my watch, for it was growing late.

"Well, now I have told you how I would have peopled Mars had the order been sent to me here to do it," said the doctor, "will you go along with me, and see how nearly I am right?"

"I am afraid not," I replied; "my business ties forbid. However, I want to see you make the start and the moment you return!"