Lumen. It is to hear your reflections that I give you this narrative.
Quærens. I want to ask you if the same inversion would take place with the hearing as well as the sight? If you can see an event backwards from its real occurrence, can you also hear a discourse backwards, beginning at the end? This is perhaps a daring question, and apparently ridiculous, but in paradoxes where can one stop?
Light and sound.
Lumen. The paradox is only apparent. The laws of sound are essentially different from the laws of light. Sound travels only at the rate of 340 metres a second, and its effects have absolutely nothing in common with those of light. Nevertheless it is evident that if we were to advance into the air with a velocity superior to that of sound, we should hear inversely the sounds that left the lips of a speaker. If, for instance, some one were to recite an alexandrine, an auditor in moving with the aforesaid velocity, starting at the moment when he heard the last foot of the line, would find successively the eleven other feet which had been uttered before, and would thus hear the alexandrine backwards.
As to the theory itself, it suggests a curious reflection, that nature might have caused sound to travel, not at the rate of 340 metres a second, and that its velocity, which depends on the density and the elasticity of the air, might have been very much less. Why, for instance, might it not have been transmitted at the rate of only a few centimetres a second? Now see what would be the result if this were the case. Men would not be able to speak to one another when walking together. Let two friends be conversing, and suppose one takes a step or two in advance, or goes on, say the distance of a metre; now, if sound were to take many seconds to cross this metre, the consequence would be that, instead of hearing the phrases spoken in their right order by his friend, the foremost walker would hear in an inverse order the sounds conveying the anterior phrases. In that case we could not speak whilst walking, and three-fourths of mankind would not be able to hear one another.
These remarks, my friend, induce me to suggest to you, in this connection, for your consideration, a subject well worthy of attention, and which has hitherto received little notice—that of the adaptation of the human organism to its terrestrial environment. The manner in which man sees, in which he hears; his sensations, his nervous system, his build, his weight, his density, his walk, his functions—in a word, all his actions are regulated and constituted by the condition of your planet. None of your acts are absolutely free and independent. Man is the obedient, though unconscious, creature of the organic forces of the Earth.
The human organism derived from the Earth.
Organic life accords with its habitat on each planet.
Undoubtedly the human soul, not being a function of the brain, and existing by itself, enjoys relative liberty; but this liberty is limited by its faculties, its powers, and its energies; it is determined, according to the causes which decide it, at the moment of the birth of every man. Could one know exactly the faculties of his soul and the circumstances which were to surround his life, one could write beforehand that man's life in all its details. The human organism is the product of the planet. It is not by a Divine fantasy, by a miracle, or by a direct creation that terrestrial man is constituted such as he is. His form, his figure, his weight, his sense, his whole organisation, are derived from the state or condition of your planet, the atmosphere that you breathe, the food that nourishes you, the gravity of the surface of the Earth, the density of terrestrial matter, &c. The human body does not differ anatomically from that of one of the higher mammalia, and if you go back to the origin of species, you will find gradual transformations established by unimpeachable evidence. The whole of terrestrial life, from the mollusc to man, is the development of one single and sole genealogical tree. The human form has its origin in the animal form. Man is the butterfly developed from the chrysalis of the palæontological ages. From this fact the consequence results that on other worlds organic life is different from what it is here, and that their humanities, which, like our own, are the result of forces in activity on each planet, differ absolutely in their forms from that of terrestrial humanity. For example, on the worlds where they do not eat, the digestive apparatus and the intestines do not exist. On the worlds which are very highly electric, the beings inhabiting them are gifted with an electric sense. On others, sight is adapted for the ultra-violet rays, and the eyes have nothing in common with your eyes; they do not see what you see, and they see what you cannot see. The organs are adapted to the functions they have to fulfil.
Quærens. We are not, then, the absolute type of creation? Creation itself is, it appears, a perpetual development of forces in activity.