The fact that density is very slight on the surface of that world, and that the constituent particles of bodies are less heavy there than here, has permitted the formation of beings of incomparably less weight, more aerial, more delicate, more sensitive. The fact that the atmosphere is nutritive has freed Martial organisms from the coarseness of earthly needs. It is an entirely different state of things. The light there is less bright, that planet being farther from the Sun than we, and the optic nerve is more sensitive. Electric and magnetic influences being very intense, the inhabitants possess senses unknown to terrestrial organizations,--senses which put them into communication with these influences. Everything is evenly balanced in Nature. Beings are everywhere adapted to their surroundings and to the soil from which they spring. Organisms can no more be earthly on Mars than they could be aerial at the bottom of the sea. More than that, the condition of superiority generated by this nature of things is developed of itself by the facility by which all intellectual work is accomplished. Nature seems to obey thought. The architect desirous of erecting a building, the engineer who wants to change the surface of the ground, either to lower or to raise, to cut down mountains or fill up valleys, does not strike against material weight and material difficulties, as he does here. Art, too, has made the most rapid progress from the beginning. And yet more. Martial humanity, being several hundreds of thousands of years older than terrestrial humanity, went through all the phases of its development before we did; our real scientific progress, even the most transcendent, is but a child's foolish toy, compared to the science of the inhabitants of that planet. In astronomy, especially, they are incomparably more advanced than we, and know the Earth much better than we know their home. They have invented, among other things, a kind of tele-photographic apparatus, in which a roll of stuff constantly receives the picture of our world, and is impressed by it unalterably as it unrolls. An immense museum, devoted especially to the planets of the solar system, preserves all these photographic pictures, fixed forever in chronological order. All the Earth's history is to be found there,--France in the time of Charlemagne, Greece in the days of Alexander, Egypt under Rameses. By the microscope the smallest details can be made out, such as Paris during the French Revolution, Rome under the pontificate of Borgia, Christopher Columbus's Spanish fleet reaching America, the Francs of Clovis taking possession of the Gauls, Julius Cæsar's army stopped in its conquest of England by the tide which washed away his ships, the troops of King David, the founder of standing armies, as well as most historic scenes, recognizable from special characters of their own.