Astronomical Myths Part 9

The various portions of the general soul of the universe resided, according to Timaeus, in the different planets, and depended on their various characters. Some portions were in the moon, others in Mercury, Venus, or Mars, and so on, and thus they give rise to the various characters and dispositions that are seen among men. But to these parts of the human soul that are taken from the planets is joined a spark of the supreme Divinity, which is above them all, and this makes man a more holy animal than all the rest, and enables him to have immediate converse with the Deity himself. All the different substances in nature were supposed to be endowed with more or less of this soul, according to their material nature or subtilty, and were placed in the same order along the line, from the centre to the circ.u.mference, on which the planets were situated, as we have seen above. In the centre was the earth, the heaviest and grossest of all, which had but little if any soul at all. Between the earth and the moon, Timaeus placed first water, then the air, and lastly elementary fire, which he considered to be principles, which were less material in proportion as they were more remote and partook of a larger quant.i.ty of the soul of the universe.

Beyond the moon came all the planets, and thus were filled up the greater number of the harmonic degrees, the motions of the various bodies being guided by the principle enunciated above.

When we carefully consider this theory we find that by a slight change of name we may bring it more into harmony with modern ideas. It would appear indeed that the ancients called that "soul" which we now call "force," and while we say that this force of attraction is in proportion to the ma.s.ses and the inverse square of the distance, they put it that it was proportional to the matter, and to the divine substance on which the distance depended. So that we may interpret Timaeus as stating this proposition: _The distances of the stars and their forces are proportional among themselves to their periodic times._ "Some people,"

says Plutarch, "seek the proportions of the soul of the universe in the velocities (or periodic times), others in the distances from the centre; some in the ma.s.ses of the heavenly bodies, and others more acute in the ratios of the diameters of their orbits. It is probable that the ma.s.s of each planet, the intervals between the spheres and the velocities of their motions, are like well-tuned musical instruments, all proportional harmonically with each other and with all other parts of the universe, and by necessary consequence that there are the same relative proportions in the soul of the universe by which they were formed by the Deity."

It is marvellous how deeply occupied were all the best minds in Greece and Italy on this subject, both poets and philosophers; Ocellus, Democritus, Timaeus, Aristotle, and Lucretius have all left treatises on the same subject, and almost with the same t.i.tle, "The Nature of the Universe."

Though somewhat similar to that of Timaeus, it will be interesting to give an account of the ideas of one of these, Ocellus of Lucania.

Ocellus represents the universe as having a spherical form. This sphere is divided into concentric layers; above that of the moon they were called celestial spheres, while below it and inwards as far as the centre of the earth they were called the elementary spheres, and the earth was the centre of them all.

In the celestial spheres all the stars were situated, which were so many G.o.ds, and among them the sun, the largest and most powerful of all. In these spheres is never any disturbance, storm, or destruction, and consequently no reparation, no reproduction, no action of any kind was required on the part of the G.o.ds. Below the moon all is at war, all is destroyed and reconstructed, and here therefore it is that generations are possible. But these take place under the influence of the stars, and particularly that of the sun, which in its course acts in different ways on the elementary spheres, and produces continual variations in them, from whence arises the replenis.h.i.+ng and diversifying of nature. It is the sun that lights up the region of fire, that dilates the air, melts the water, and renders fertile the earth, in its daily course from east to west, as well as in this annual journey into the two tropics. But to what does the earth owe its germs and its species? According to some philosophers these germs were celestial ideas which both G.o.ds and demons scattered from above over every part of nature, but according to Ocellus they arise continually under the influence of the heavenly bodies. The divisions of the heavens were supposed to separate the portion that is unalterable from that which is in ceaseless change. The line dividing the mortal from the immortal is that described by the moon: all that lies above that, inclusive, is the habitation of the G.o.ds; all that lies below is the abode of nature and discord; the latter tending constantly to destruction, the former to the reconstruction of all created things.

Ideas such as these, of which we could give other examples more remotely connected with harmony, whatever amount of truth we may discover in them, prove themselves to have been made before the sciences of observation had enabled men to make anything better than empty theories, and to support them with false logic. No better example of the latter can perhaps be mentioned here than the way in which Ocellus pretends to prove that the world is eternal. "The universe," he says, "_having_ always existed, it follows that everything in it and every arrangement of it must always have been as it is now. The several parts of the universe _having_ always existed with it, we may say the same of the parts of these parts; thus the sun, the moon, the fixed stars, and the planets have always existed with the heavens; animals, vegetables, gold, and silver with the earth; the currents of air, winds, and changes from hot to cold, from cold to hot, with the air. _Therefore_ the heaven, with all that it now contains; the earth, with all that it produces and supports; and lastly, the whole aerial region, with all its phenomena, have always existed." When this system of argument pa.s.sed away, and exact observation took its place, it was soon found that so far from what the ancients had argued _must be_ really being the case, no such relation as they indicated between the distances or velocities of the planets could be traced, and therefore no harmony in the heavens in this sense. It is not indeed that we can say no sounds exist because we hear none; but considering harmony really to consist of the relations of numbers, no such relations exist between the planets' distances, as measured now of course from the sun, instead of being, as then, imagined from the earth.

The gamut is nothing else than the series of numbers:--

do re mi fa sol la si do 1 9/8 5/4 4/3 3/2 5/3 15/8 2

and is independent of our perception of the corresponding notes. A concert played before a deaf a.s.sembly would be a concert still. If one note is made by 10,000 vibrations per second, and another by 20,000, we should hear them as an octave, but if one had only 10 and the other 20, they would still be an octave, though inaudible as notes to us; so too we may speak even of the harmony of luminous vibrations of ether, though they do not affect our ears.

The velocities of the planets do not coincide with the terms of this series. The nearer they are to the sun the faster is their motion, Mercury travelling at the mean rate of 55,000 metres a second, Venus, 36,800, the earth 30,550, Mars 24,448, Jupiter 13,000, Saturn 9,840, Ura.n.u.s 6,800, and Neptune 5,500, numbers which are in the proportion roundly of 100, 67, 55, 44, 24, 16, 12, 10, which have no sufficient relation to the terms of an harmonic series, to make any harmony obvious.

Returning, however, to the ancient philosophers, we are led by their ideas about the soul of the universe to discover the origin of their G.o.ds and natural religion. They were persuaded that only living things could move, and consequently that the moving stars must be endowed with superior intelligence. It may very well be that from the number seven of the planets, including the sun and moon, which were their earliest G.o.ds, arose the respect and superst.i.tion with which all nations, and especially the Orientals, regarded that number. From these arose the seven superior angels that are found in the theologies of the Chaldeans, Persians, and Arabians; the seven gates of Mithra, through which all souls must pa.s.s to reach the abode of bliss; the seven worlds of purification of the Indians, and all the other applications of the number seven which so largely figure in Judaism, and have descended from it to our own time. On the other hand, as we have seen, this number seven may have been derived from the number of the stars in the Pleiades.

We have noticed in our chapter on the History of the Zodiac how the various signs as they came round and were thought to influence the weather and other natural phenomena, came at last to be wors.h.i.+pped. Not less, of course, were the sun and moon deified, and that by nations who had no zodiac. Among the Egyptians the sun was painted in different forms according to the time of year, very much as he is represented in our own days in pictures of the old and new years. At the winter solstice with them he was an infant, at the spring equinox he was a young man, in summer a man in full age with flowing beard, and in the autumn an old man. Their fable of Osiris was founded on the same idea.

They represented the sun by the hawk, and the moon by the Ibis, and to these two, wors.h.i.+pped under the names of Osiris and Isis they attributed the government of the world, and built a city, Heliopolis, to the former, in the temple of which they placed his statue.

The Phenicians in the same way, who were much influenced by ideas of religion, attributed divinity to the sun, moon, and stars, and regarded them as the sole causes of the production and destruction of all things.

The sun, under the name of Hercules, was their great divinity.

The Ethiopians wors.h.i.+pped the same, and erected the famous table of the sun. Those who lived above Meroe, admitted the existence of eternal and incorruptible G.o.ds, among which they included the sun, moon, and the universe. Like the Incas of Peru, they called themselves the children of the sun, whom they regarded as their common father.

The moon was the great divinity of the Arabs. The Saracens called it Cabar, or the great, and its crescent still adorns the religious monuments of the Turks. Each of their tribes was under the protection of some particular star. Sabeism was the princ.i.p.al religion of the east.

The heavens and the stars were its first object.

In reading the sacred books of the ancient Persians contained in the _Zendavesta_, we find on every page invocations addressed to Mithra, to the moon, the stars, the elements, the mountains, the trees, and every part of nature. The ethereal fire circulating through all the universe, and of which the sun is the princ.i.p.al focus, was represented among the fire-wors.h.i.+ppers by the sacred and perpetual fire of their priests. Each planet had its own particular temple, where incense was burnt in its honour. These ancient peoples embodied in their religious systems the ideas which, as we have seen, led among the Greeks to the representation of the harmony of heaven. All the world seemed to them animated by a principle of life which circulated through all parts, and which preserved it in an eternal activity. They thought that the universe lived like man and the other animals, or rather that these latter only lived because the universe was essentially alive, and communicated to them for an instant an infinitely small portion of its own immortality.

They were not wise, it may be, in this, but they appear to have caught some of the ideas that lie at the basis of religious thought, and to have traced harmony where we have almost lost the perception of it.

CHAPTER VIII.

ASTRONOMICAL SYSTEMS.

In our former chapters we have gained some idea of the general structure of the heavens as represented by ancient philosophers, and we no longer require to know what was thought in the infancy of astronomy, when any ideas promulgated were more or less random ones; but in this chapter we hope to discuss those arrangements of the heavenly bodies which have been promulgated by men as complete systems, and were supposed to represent the totality of the facts.

The earliest thoroughly-established system is that of Ptolemy. It was not indeed invented by him. The main ideas had been entertained long before his time, but he gave it consistence and a name.

We obtain an excellent view of the general nature of this system from Cicero. He writes:--

"The universe is composed of nine circles, or rather of nine moving globes. The outermost sphere is that of the heavens which surrounds all the others, and on which are fixed the stars. Beneath this revolve seven other globes, carried round by a motion in a direction contrary to that of the heavens. On the first circle revolves the star which men call Saturn; on the second Jupiter s.h.i.+nes, that beneficent and propitious star to human eyes; then follows Mars, ruddy and awful.

Below, and occupying the middle region, revolves the Sun, the chief, prince, and moderator of the other stars, the soul of the world, whose immense globe spreads its light through s.p.a.ce. After him come, like two companions, Venus and Mercury. Lastly, the lowest globe is occupied by the moon, which borrows its light from the star of day. Below this last celestial circle, there is nothing but what is mortal and corruptible, except the souls given by a beneficent Divinity to the race of men.

Above the moon all is eternal. The earth, situated in the centre of the world, and separated from heaven on all sides, forms the ninth sphere; it remains immovable, and all heavy bodies are drawn to it by their own weight."

The earth, we should add, is surrounded by the sphere of air, and then by that of fire, and by that of ether and the meteors.

With respect to the motions of these spheres. The first circle described about the terrestrial system, namely, that of the moon, was accomplished in 27 days, 7 hours, and 43 minutes. Next to the moon, Mercury in the second, and Venus in the third, and the sun in the fourth circle, all turned about the earth in the same time, 365 days, 5 hours, and 49 minutes. But these planets, in addition to the general movement, which carried them in 24 hours round from east to west and west to east, and the annual revolution, which made them run through the zodiacal circle, had a third motion by which they described a circle about each point of their orbit taken as a centre.

[Ill.u.s.tration: FIG. 14.--PTOLEMY'S ASTRONOMICAL SYSTEM.]

The fifth sphere, carrying Mars, accomplished its revolution in two years. Jupiter took 11 years, 313 days, and 19 hours to complete his...o...b..t, and Saturn in the seventh sphere took 29 years and 169 days.

Above all the planets came the sphere of the fixed stars, or Firmament, turning from east to west in 24 hours with inconceivable rapidity, and endued also with a proper motion from west to east, which was measured by Hipparchus, and which we now call the precession of the equinoxes, and know that it has a period of 25,870 years. Above all these spheres, a _primum mobile_ gave motion to the whole machine, making it turn from east to west, but each planet and each fixed star made an effort against this motion, by means of which each of them accomplished their revolution about the earth in greater or less time, according to its distance, or the magnitude of the orbit it had to accomplish.

One immense difficulty attended this system. The apparent motions of the planets is not uniform, for sometimes they are seen to advance from west to east, when their motion is called _direct_, sometimes they are seen for several nights in succession at the same point in the heavens, when they are called _stationary_, and sometimes they return from east to west, and then their motion is called _retrograde_.

We know now that this apparent variation in the motion of the planets is simply due to the annual motion of the earth in its...o...b..t round the sun.

For example, Saturn describes its vast orbit in about thirty years, and the earth describes in one year a much smaller one inside. Now if the earth goes faster in the same direction as Saturn, it is plain that Saturn will be left behind and appear to go backwards, while if the earth is going in the same direction the velocity of Saturn will appear to be decreased, but his direction of motion will appear unaltered.

To explain these variations, however, according to his system, Ptolemy supposed that the planets did not move exactly in the circ.u.mference of their respective orbits, but about an _ideal centre_, which itself moved along this circ.u.mference. Instead therefore of describing a circle, they described parts of a series of small circles, which would combine, as is easy to see, into a series of uninterrupted waves, and these he called _Epicycles_.

Another objection, which even this arrangement did not overcome, was the variation of the size of the planets. To overcome this Hipparchus gave to the sphere of each planet a considerable thickness, and saw that the planet did not turn centrally round the earth, but round a centre of motion placed outside the earth. Its revolution took place in such a manner, that at one time it reached the inner boundary, at another time the outer boundary of its spherical heaven.

But this reply was not satisfactory, for the differences in the apparent sizes proved by the laws of optics such a prodigious difference between their distances from the earth at the times of conjunction and opposition, that it would be extremely difficult to imagine spheres thick enough to allow of it.

It was a gigantic and formidable piece of machinery to which it was necessary to be continually adding fresh pieces to make observation accord with theory. In the thirteenth century, in the times of the King-Astronomer, Alphonso X. of Castile, there were already seventy-five circles, one within the other. It is said that one day he exclaimed, in a full a.s.semblage of bishops, that if the Deity had done him the honour to ask his advice before creating the world, he could have told Him how to make it a little better, or at all events more simply. He meant to express how unworthy this complication was of the dignity of nature.

[Ill.u.s.tration: FIG. 15.--THE EPICYCLES OF PTOLEMY.]

Fracastor, in his _h.o.m.ocentrics_, says that nothing is more monstrous or absurd than all the excentrics and epicycles of Ptolemy, and proposes to explain the difference of velocity in the planets at different parts of their orbits by the medium offering greater or less resistance, and their alteration in apparent size by the effect of refraction.

The essential element of this system was that it took appearances for realities, and was founded on the a.s.sumption that the earth is fixed in the centre of the universe, and of course therefore neglected all the appearances produced by its motion, or had to explain them by some peculiarity in the other planets.

Although it was corrected from time to time to make it accord better with observation, it was the same essentially that was taught officially everywhere. It reigned supreme in Egypt, Greece, Italy, and Arabia, and in the great school of Alexandria, which consolidated it and enriched it by its own observations.

But though the same in essence, the details, and especially the means of overcoming the difficulties raised by increased observations, have much varied, and it will be interesting and instructive to record some of the chief of them.

One of the most important influences in modifying the astronomical systems taught to the world has been that of the Fathers of the Christian Church. When, after five centuries of patient toil, of hopes, ambitions, and discussions, the Christian Church took possession of the thrones and consciences of men, they founded their physical edifice on the ancient system, which they adapted to their special wants. With them Aristotle and Ptolemy reigned supreme. They decreed that the earth const.i.tuted the universe, that the heavens were made for it, that G.o.d, the angels, and the saints inhabited an eternal abode of joy situated above the azure sphere of the fixed stars, and they embodied this gratifying illusion in all their illuminated ma.n.u.scripts, their calendars, and their church windows.

The doctors of the Church all acknowledged a plurality of heavens, but they differed as to the number. St. Hilary of Poitiers would not fix it, and the same doubt held St. Basil back; but the rest, for the most part borrowing their ideas from paganism, said there were six or seven, or up to ten. They considered these heavens to be so many hemispheres supported on the earth, and gave to each a different name. In the system of Bede, which had many adherents, they were the Air, Ether, Fiery s.p.a.ce, Firmament, Heaven of the Angels, and Heaven of the Trinity.

The two chief varieties in the systems of the middle ages may be represented as follows:--

Those who wished to have everything as complete as possible combined the system of Ptolemy with that of the Fathers of the Church, and placed in the centre of the earth the infernal regions which they surrounded by a circle. Another circle marked the earth itself, and after that the surrounding ocean, marked as water, then the circle of air, and lastly that of fire. Enveloping these, and following one after the other, were the seven circles of the seven planets; the eighth represented the sphere of the fixed stars on the firmament, then came the ninth heaven, then a tenth, the _coelum cristallinum_, and lastly an eleventh and outermost, which was the empyreal heaven, where dwelt the cherubim and seraphim, and above all the spheres was a throne on which sat the Father, as Jupiter Olympus.

The others who wished for more simplicity, represented the earth in the centre of the universe, with a circle to indicate the ocean, the second sphere was that of the moon; the third was that of the sun; on the fourth were placed the four planets, Jupiter, Mars, Venus and Mercury; there was a fifth for the s.p.a.ce outside the planets, and the last outside one was the firmament; altogether seven spheres instead of eleven. As a specimen of the style of representation of the astronomical systems of the middle ages, we may take the figure on the following page:--