ANCIENT AND MODERN SYSTEMS OF THE WORLD.

— The first idea that men formed of the Earth, of the movement of the heavenly bodies, and of the constitution of the Universe must, at the outset, have been based solely on what the senses perceived.

Ignorant of the most elementary laws of Physics and of the forces of Nature, having only sight as a means of observation, they could judge by appearances alone.

Seeing the Sun appear in the morning on one side of the horizon, and disappear in the evening on the opposite side, they naturally concluded that it revolved around the Earth, the latter remaining motionless.

If they had then been told that the contrary is what occurs, they would have answered that such a thing was not possible, objecting: we see that the Sun changes place and we do not feel that the Earth moves.

— The small extent of journeys, which in those days rarely went beyond the limits of the tribe or of the valley, did not allow the sphericity of the Earth to be verified.

How, moreover, were they to suppose that the Earth was a ball? Beings, in such a case, could keep themselves only at the highest point and, supposing it inhabited over its whole surface, how would they live in the opposite hemisphere, with their heads down and their feet up?

Still less possible would this have seemed with the movement of rotation. When, even in our own days, in which the law of gravitation is known, one sees relatively enlightened persons not perceive this phenomenon, how can we be surprised that men of the earliest ages did not even suspect it?

For them, therefore, the Earth was a flat and circular surface, like a millstone, extending out of sight in the horizontal direction. Hence the expression still in use: To go to the end of the world. They were unacquainted with its limits, its thickness, its interior, its lower face, what lay beneath it. n

— Because it presented itself in a concave form, the sky, in the common belief, was held to be a real vault, whose lower edges rested on the Earth and marked its confines, a vast dome whose capacity the air completely filled.

With no notion of infinite space, incapable even of conceiving it, men imagined that this vault was constituted of solid matter, whence the denomination of firmament that was given to it and that has survived the belief, signifying: firm, resistant (from the Latin firmamentum, derived from firmus, and from the Greek herma, hermatos, firm, prop, support, point of support).

— The stars, of whose nature they could form no suspicion, were simply luminous points, of diverse volumes, set into the vault, like suspended lamps, arranged upon a single surface and, consequently, all at the same distance from the Earth, just like those seen on the interior of certain domes, painted blue, representing that of the sky.

Although today the ideas are different, the use of the old expressions has been preserved. One still says, by comparison: the starry vault; under the dome of the sky.

— Equally unknown then was the formation of clouds by the evaporation of the waters of the Earth; it could occur to no one that the rain that falls from the sky had its origin in the Earth, whence no one saw it rise.

Hence the belief in the existence of upper waters and lower waters, of celestial springs and terrestrial springs, of reservoirs placed in the high regions, a supposition that agreed perfectly with the idea of a solid vault, capable of sustaining them. The upper waters, escaping through the crevices of the vault, fell as rain and, according as the crevices were more or less wide, the rain was gentle, torrential, or diluvian.

— Complete ignorance of the whole of the Universe and of the laws that govern it, of the nature, the constitution, and the destination of the heavenly bodies—which, moreover, seemed so small compared with the Earth—necessarily caused the latter to be considered as the principal thing, the sole end of Creation, and the heavenly bodies as accessories, created exclusively on behalf of its inhabitants.

This prejudice has perpetuated itself down to our own days, despite the discoveries of Science, which have changed, for man, the aspect of the world. How many people still believe that the stars are ornaments of the sky, destined to delight the sight of the inhabitants of the Earth!

— It was not long, however, before they noticed the apparent movement of the stars, which shift en masse from east to west, emerging at nightfall and concealing themselves in the morning, and keeping their respective positions.

Such an observation, nevertheless, for a long time had no consequence other than to confirm the idea of a solid vault, dragging the stars along with it in its movement of rotation.

These primary, simplistic ideas constituted, in the course of long secular periods, the foundation of religious beliefs and served as the basis for all the ancient cosmogonies.

— Later, from the direction of the movement of the stars and from their periodic return, in the same order, it was perceived that the celestial vault could not be merely a hemisphere placed over the Earth, but an entire sphere, hollow, in whose center the Earth lay, still flat, or, at most, convex and inhabited only on the upper surface. This was already a progress.

But what was the support of the Earth? It would be useless to mention all the ridiculous suppositions engendered by the imagination, from that of the Indians, who said it was supported by four white elephants, these resting on the wings of an immense vulture. The more sensible confessed that they knew nothing about it.

— Meanwhile, an opinion generally widespread in the pagan theogonies situated in the low places, or rather in the depths of the Earth, or beneath it—it did not quite know—the abode of the reprobate, called inferno, that is, lower places, and in the high places, beyond the region of the stars, the abode of the blessed.

The word inferno has been preserved down to our own days, although it has lost its etymological signification, ever since Geology removed from the bowels of the Earth the place of eternal torments and Astronomy demonstrated that in infinite space there is neither below nor above.

— Under the pure sky of Chaldea, of India, and of Egypt, cradle of the most ancient civilizations, the movement of the heavenly bodies was observed with as much exactness as the lack of special instruments permitted.

It was noticed, first of all, that certain stars had their own movement, independent of it, which did not allow the supposition that they were fixed to the vault; they were called wandering stars or planets, to distinguish them from the fixed stars. Their movements and periodic returns were calculated.

In the diurnal movement of the starry sphere, the immobility of the Pole Star was noticed, around which the others described, in twenty-four hours, parallel oblique circles, some larger, others smaller, according to the distance at which they were found from the central star; this was the first step toward knowledge of the obliquity of the axis of the world.

Longer journeys gave occasion for the difference of the aspects of the sky to be observed, according to latitudes and seasons; the verification that the elevation of the Pole Star above the horizon varied with latitude opened the way to the perception of the roundness of the Earth; it was thus that, little by little, they came to form a more exact idea of the system of the world.

About the year 600 before Jesus Christ, Thales of Miletus (Asia Minor) discovered the sphericity of the Earth, the obliquity of the ecliptic, and the cause of eclipses.

A century later, Pythagoras of Samos discovered the diurnal movement of the Earth upon its own axis, its annual movement around the Sun, and incorporated the planets and the comets into the solar system.

Hipparchus of Alexandria (Egypt), 160 years before Jesus Christ, invented the astrolabe, calculated and predicted eclipses, observed the spots of the Sun, determined the tropical year, the duration of the revolutions of the Moon.

Although most precious for the progress of Science, these discoveries took nearly 2,000 years to become popularized.

Having then only rare manuscripts to propagate themselves, the new ideas remained as the patrimony of a few philosophers, who taught them to privileged disciples; the masses, whom no one took care to enlighten, derived no benefit from them and continued to nourish themselves on the old beliefs.

— About the year 140 of the Christian era, Ptolemy, one of the most illustrious men of the School of Alexandria, combining his own ideas with the common beliefs and with some of the most recent astronomical discoveries, composed a system that may be qualified as mixed, which bears his name and which, for nearly fifteen centuries, was the only one that the civilized world adopted.

According to the system of Ptolemy, the Earth is a sphere placed in the center of the Universe and composed of four elements: earth, water, air, and fire. This is the first region, called elementary. The second region, called ethereal, comprised eleven heavens, or concentric spheres, revolving around the Earth, namely: the heaven of the Moon, those of Mercury, of Venus, of the Sun, of Mars, of Jupiter, of Saturn, of the fixed stars, of the first crystalline, a transparent solid sphere; of the second crystalline and, finally, of the prime mover, which gave movement to all the lower heavens and obliged them to make a revolution in twenty-four hours.

Beyond the eleven heavens was the Empyrean, dwelling of the blessed, a denomination taken from the Greek pyr or pur, which means fire! because it was believed that this region shone with light, like fire.

For a long time the belief prevailed in many superposed heavens, whose number, however, varied. The seventh was generally held to be the highest, whence the expression: to be transported to the seventh heaven. Saint Paul said that he had been raised to the third heaven.

Apart from the common movement, the heavenly bodies, according to Ptolemy, had their own movements, more or less extended, according to the distance at which they were from the center.

The fixed stars made a revolution in 25,816 years, an evaluation that denotes knowledge of the precession of the equinoxes, which is accomplished in 25,868 years.

— At the beginning of the sixteenth century, Copernicus, a celebrated astronomer, born at Thorn (Prussia) in the year 1472 and dead in that of 1543, reconsidered the ideas of Pythagoras and conceived a system which, confirmed every day by new observations, met with a favorable reception and was not long in supplanting that of Ptolemy.

According to the system of Copernicus, the Sun is in the center, and around it the heavenly bodies describe circular orbits, the Moon being a satellite of the Earth.

A century having elapsed, in 1609, Galileo, a native of Florence, invented the telescope; in 1610, he discovered the four satellites of Jupiter and calculated their revolutions; he recognized that the planets do not have light of their own like the stars, but that they are illuminated by the Sun; that they are spheres similar to the Earth; he observed their phases and determined the time that their rotations around their axes last, thus offering, by material proofs, definitive sanction to the system of Copernicus.

The construction of the superposed heavens then collapsed; it was recognized that the planets are worlds similar to the Earth and, no doubt, inhabited like it; that the stars are innumerable suns, probable centers of so many other planetary systems, the Sun itself being recognized as a star, center of a whirl of planets that are subject to it.

The stars ceased to be confined within a zone of the celestial sphere, to be irregularly disseminated throughout limitless space, those that seem to touch one another being found at immeasurable distances from each other, the apparently smaller ones being the most distant from us and the larger ones being those nearest to us, but, even so, at hundreds of billions of leagues.

The groups that have taken the name of constellations are no more than apparent aggregates, caused by distance: their figures are merely effects of perspective, like those that lights scattered over a vast plain, or the trees of a forest, form to the eyes of one who observes them placed at a fixed point. In reality, however, such groupings do not exist. If we could transport ourselves to the gathering of one of these constellations, as we approached it, its form would dissolve and new groups would draw themselves to our view.

Now, since these groupings exist only in appearance, the signification that a superstitious common belief attributes to them is illusory and can exist only in the imagination.

To distinguish the constellations, names such as these were given to them: Leo, Taurus, Gemini, Virgo, Libra, Capricorn, Cancer, Orion, Hercules, the Great Bear or Chariot of David, the Little Bear, Lyra, etc., and, to represent them, there were attributed to them the forms that these names recall, fanciful for the most part and, in no case, keeping any relation with the groups of stars so called. It would be useless, then, to look in the sky for such forms.

The belief in the influence of the constellations, above all of those that constitute the twelve signs of the zodiac, came from the idea attached to the names they bear. If the one called the lion had been given the name of the ass or of the sheep, they would certainly have attributed another influence to it.

— Beginning with Copernicus and Galileo, the old cosmogonies ceased forever to subsist: Astronomy could only advance, not retreat.

History tells of the struggles that these men of genius had to sustain against prejudices and, above all, against the spirit of sect, interested in maintaining errors upon which beliefs had been founded, supposedly established on unshakable bases.

The invention of an optical instrument sufficed to overthrow a construction of many thousands of years.

Nothing, of course, could prevail against a truth recognized as such.

Thanks to printing, the public, initiated into the new ideas, began not to let itself be lulled with illusions and took part in the struggle; it was no longer against individuals that the upholders of the old ideas had to combat, but against the general opinion, which espoused the cause of truth.

How great is the Universe in the face of the paltry proportions that our fathers assigned to it! How sublime is the work of God, when we see it accomplished in conformity with the eternal laws of Nature! But, also, how much time, how many efforts of genius, how much devotion were needed to open the eyes of creatures and to tear from them, at last, the blindfold of ignorance!

— From then on the way was open into which illustrious and numerous savants would enter, in order to complete the work begun.

In Germany, Kepler discovered the celebrated laws that preserve his name and by means of which it is recognized that the orbits that the planets describe are not circular, but ellipses, one of whose foci the Sun occupies.

Newton, in England, discovered the law of universal gravitation.

Laplace, in France, created celestial mechanics. Finally, Astronomy ceased to be a system founded on conjectures or probabilities and became a science established on the most rigorous bases, those of calculation and geometry.

Thus was laid one of the foundation stones of Genesis, about 3,300 years after Moses. [1] “Hindu mythology taught that, in the evening, the star of day divested itself of its light and crossed the sky during the night with a darkened face. Greek mythology depicted the chariot of Apollo as drawn by four horses. Anaximander of Miletus maintained, according to Plutarch, that the Sun was a chariot full of very vivid fire, which escaped through a circular opening. Epicurus, according to some, would have emitted the opinion that the Sun kindled itself in the morning and was extinguished at night in the waters of the ocean; according to others, he considered this heavenly body a pumice stone heated to incandescence. Anaxagoras took it for a piece of red-hot iron, the size of the Peloponnese. A singular thing! the ancients were so invincibly led to consider real the apparent magnitude of this heavenly body that they persecuted the rash philosopher for having attributed that volume to the torch of day, all the authority of Pericles being needed to save him from a condemnation to death and for that penalty to be commuted to one of exile.” (Flammarion, Studies and Readings on Astronomy, p. 6.) In the face of such ideas, emitted in the fifth century before Christ, at the time of the greatest prosperity of Greece, those that the men of the earliest ages formed about the system of the world ought not to cause astonishment.