Early Conceptions of the Cosmos
Week 2 Reading for Foundations of Computing and Communication
Koestler, Arthur. (1959/1972). The Sleepwalkers: A History of Man's changing vision of the Universe. Penguin Books, London. pp19-25.
We can add to our knowledge, but we cannot subtract from it. When I try to see the Universe as a Babylonian saw it around 3000 B.C., I must grope my way back to my own childhood. At the age of about four I had what I felt to be a satisfactory understanding of God and the world. I remember an occasion when my father pointed his finger at the white ceiling, which was decorated with a frieze of dancing figures, and explained that God was up there, watching me. I immediately became convinced that the dancers were God and henceforth addressed my prayers to them, asking for their protection against the terrors of day and night. Much in the same manner, I like to imagine, did the luminous figures on the dark ceiling of the world appear as living divinities to Babylonians and Egyptians. The Twins, the Bear, the Serpent were as familiar to them as my fluted dancers to me; they were thought to be not very far away, and they held power of life and death, harvest and rain.
The world of the Babylonians, Egyptians, and Hebrews was an oyster, with water underneath, and more water overhead, supported by the solid firmament. It was of moderate dimensions and as safely closed in on all sides as a cot in the nursery or a babe in the womb. The Babylonians' oyster was round, the earth was a hollow mountain, placed in its centre, floating on the waters of the deep; above it was a solid dome, covered by the upper waters. The upper waters seeped through the dome as rain, and the lower waters rose in fountains and springs. Sun, moon, and stars progressed in a slow dance across the dome, entering the scene through doors, in the East and vanishing through doors in the West.
The universe of the Egyptians was a more rectangular oyster or box; the earth was its floor, the sky was either a cow whose feet rested on the four comers of the earth, or a woman sup-
[p20] porting herself on her elbows and knees; later, a vaulted metal lid. Around the inner walls of the box, on a kind of elevated gallery, flowed a river on which the sun and moon gods sailed their barques, entering and vanishing through various stage doors. The fixed stars were lamps, suspended from the vault, or carried by other gods. The planets sailed their own boats along canals originating in the Milky Way, the celestial twin of the Nile. Towards the fifteenth of each month, the moon god was attacked by a ferocious sow, and devoured in a fortnight of agony; then he was re‑born again. Sometimes the sow swallowed him whole, causing a lunar eclipse; sometimes a serpent swallowed the sun, causing a solar eclipse. But these tragedies were, like those in a dream, both real and not; inside his box or womb, the dreamer felt fairly safe.
This feeling of safety was derived from the discovery that, in spite of the tumultuous private lives of, the sun and moon gods, their appearances and movements remained utterly dependable and predictable. They brought night and day, the seasons and the rain, harvest, and sowing time, in regular cycles. The mother leaning over the cradle is an unpredictable goddess; but her feeding breast can be depended on to appear when needed. The dreaming mind may go through wild adventures, it may travel through Olympus and Tartarus, but the pulse of the dreamer has a regular beat that can be counted. The first to learn counting the pulse of the stars were the Babylonians.
Some six thousand years ago, when the human mind was still half asleep, Chaldean priests were standing on watchtowers, scanning the stars, making maps and time‑tables of their motions. Clay tablets dating from the reign of Sargon of Akkad, around 3800 B.C., show an already old‑established astronomical tradition. The time‑tables became calendars which regulated organized activity, from the growing of crops to religious ceremonies. Their observations became amazingly precise: they computed the length of the year with a deviation of less than 0.001 per cent from the correct value, and their figures relating to the motions of sun and moon have only three times the margin of error of nineteenth‑century astronomers armed with mammoth telescopes. In this respect, theirs was an
[p21] Exact Science; their observations were verifiable, and enabled them to make precise predictions of astronomical events; though based on mythological assumptions, the theory 'worked'. Thus at the very beginning of this long journey, Science emerges in the shape of Janus, the double‑faced god, guardian of doors and gates: the face in front alert and observant, while the other, dreamy and glassy‑eyed, stares in the opposite direction.
The most fascinating objects in the sky ‑ from both points of view ‑ were the planets, or vagabond stars. Only seven of these existed among the thousands of lights suspended from the firmament. They were the Sun, the Moon, Nebo ‑Mercury, Ishtar ‑ Venus, Nergal ‑ Mars, Marduk ‑ Jupiter, and Ninib Saturn. All other stars remained stationary, fixed in the pattern of the firmament, revolving once a day round the earth-mountain, but never, changing their places in the pattern. The seven vagabond stars revolved with them, but at the same time they had a motion of their own, like flies wandering over the surface of a spinning globe. Yet they did not wander all across the sky: their movements were confined to a narrow lane, or belt, which was looped around the firmament at an angle of about twenty‑three degrees to the equator. This belt - the Zodiac ‑ was divided into twelve sections, and each section was named after a constellation of fixed stars in the neighbourhood. The Zodiac was the lovers' lane in the skies, along which the planets ambled. The passing of a planet through one of the sections had a double significance: it yielded figures for the observer's time‑table, and symbolic messages of the mythological drama played out behind the scenes. Astrology and Astronomy remain to this day complementary fields of vision of Janus sapiens.
2. Ionian Fever
Where Babylon and Egypt left off, Greece took over. At the beginning, Greek cosmology moved much on the same lines - Homer's world is another, more colourful oyster, a floating disc surrounded by Okeanus. But about the time when the texts
[p22] of the Odyssey and Iliad became consolidated in their final version, a new development started in Ionia on the Aegean coast. The sixth pre‑Christian century ‑ the miraculous century of Buddha, Confucius, and Lao‑tze, of the Ionian philosophers and Pythagoras ‑ was a turning point for the human species. A March breeze seemed to blow across this planet from China to Samos, stirring man into awareness, like the breath in Adam's nostrils. In the Ionian school of philosophy, rational thought was emerging from the mythological dream‑world. It was the beginning of the great adventure: the Promethean quest for natural explanations and rational causes, which, within the next two thousand years, would transform the species more radically than the previous two hundred thousand had done.
Thales of Miletos, who brought abstract geometry to Greece, and predicted an eclipse of the sun, believed, like Homer, that the earth was a circular disc floating on water, but he did not stop there; discarding the explanations of mythology, he asked the revolutionary question out of what basic raw material, and by what process of nature, the universe was formed. His answer was, that the basic stuff or element must be water, because all things are born from moisture, including air, which is water evaporated. Others taught that the prime material was not water, but air or fire; however, their answers were less important than the fact that they were learning to ask a new type of question, which was addressed not to an oracle, but to dumb nature. It was a wildly exhilarating game; to appreciate it, one must again travel back along one's own private time‑track to the fantasies of early adolescence when the brain, intoxicated with its newly discovered powers, let speculation run riot. 'A case in point,' Plato reports, 'is that of Thales, who, when he was star‑gazing and looking upward, fell into a well, and was rallied (so it is said) by a clever and pretty maidservant from Thrace because he was eager to know what went on in the heaven, but did not notice what was in front of him, nay, at his very feet.
The second of the Ionian philosophers, Anaximander, displays all the symptoms of the intellectual fever spreading
[p23] through Greece. His universe is no longer a closed box, but infinite in extension and duration. The raw material is none of the familiar forms of matter, but a substance without definite properties except for being indestructible and everlasting. Out of this stuff all things are developed, and into it they return; before this our world, infinite multitudes of other universes have already existed, and been dissolved again into the amorphous mass. The earth is a cylindrical column, surrounded by air; it floats upright in the centre of the universe without support or anything to stand on, yet it does not fall because, being in the centre, it has no preferred direction towards which to lean; if it did, this would disturb the symmetry and balance of the whole. The spherical heavens enclose the atmosphere 'like the bark of a tree', and there are several layers of this enclosure to accommodate the various stellar objects. But these are not what they seem, and are not 'objects' at all. The sun is merely a hole in the rim of a huge wheel. The rim is filled with fire, and as it turns round the earth, so does the hole in it ‑ a puncture in a gigantic tyre filled with flames. For the moon we are given a similar explanation; its phases are due to recurrent partial stoppages of the puncture, and so are the eclipses. The stars are pin‑holes in a dark fabric through which we glimpse, the cosmic fire filling the space between two layers of 'bark.'
It is not easy to see how the whole thing works, but it is the first approach to a mechanical model of the universe. The boat of the, sun god is replaced by the wheels of a clockwork. Yet the machinery looks as if it had been dreamed up by a surrealist painter; the punctured fire‑wheels are certainly closer to Picasso than to Newton. As we move along past other cosmologies we shall get this impression over and again.
The system of Anaximenes, who was an associate of Anaximander, is less inspired; but he seems to have been the originator of the important idea that the stars are attached 'like nails' to a transparent sphere of crystalline material, which turns round the earth 'like a hat round the head'. It sounded so plausible and convincing, that the crystal spheres were to dominate cosmology until the beginning of modem times.
[p24] The Ionian philosophers' home was Miletos in Asia Minor; but there existed rival schools in the Greek towns of Southern Italy, and rival theories within each school. The founder of the Eleatic school, Xenophanes of Kolophon, is a sceptic who wrote poetry to the age of ninety‑two, and sounds as if he had served as a model for the author of Ecclesiastes:
From earth are all things and to earth all things return. From earth and water come all of us . . . No man hath certainly known, nor shall certainly know, that which he saith about the gods and about all things; for, be that which he saith ever so perfect, yet does he not know it; all things are matters of opinion . . . Men, imagine gods to be born, and to have clothes and voices and shapes like theirs . . . Yea, the gods of the Ethiopians are black and flat‑nosed, the gods of the Thracians are red‑haired and blue‑eyed . . .Yea, if oxen and horses and lions had hands, and could shape with their hands images as men do, horses would fashion their gods as horses, and oxen as oxen . . . Homer and Hesiod have ascribed to the gods all things that are a shame and a disgrace among men, theft, adultery, deceit, and other lawless acts. . . .
As against this:
There is one God . . . neither in shape nor thought like unto mortals . . . He abideth ever in the same place motionless . . . and without effort swayeth all things by his force of mind . . .
The Ionians were optimistic, heathenly materialists; Xenophanes was a pantheist of a sorrowful brand, to whom change was an illusion, and effort vanity. His cosmology reflects his philosophical temper; it is radically different from the Ionians'. His earth is not a floating disc, or column, but is 'rooted in the infinite'. The sun and the stars have neither substance nor permanence, they are merely cloudy exhalations of the earth which have caught fire. The stars are burnt out at dawn, and in
the evening a new set of stars is formed from new exhalations. Similarly, a new sun is born every morning from the crowding together of sparks. The moon is a compressed, luminous cloud, which dissolves in a month; then a new cloud starts forming. Over different regions of the earth, there are different suns and moons, all cloudy illusions.
[p25] In this manner do the earliest rational theories of the Universe betray the bias and temperament of their makers. It is generally believed that with the progress of scientific method, the theories became more objective and reliable. Whether this belief is justified, we shall see. But a propos of Xenophanes we may note that two thousand years later Galileo also insisted on regarding comets as atmospheric illusions ‑ for purely personal reasons, and against the evidence of his telescope.
Neither the cosmology of Anaxagoras, nor of Xenophanes, gained a considerable following. Every philosopher of the period seems to have had his own theory regarding the nature of the universe around 'him. To quote Professor Burnet, 'no sooner did an Ionian philosopher learn half a dozen geometrical propositions and hear that the phenomena of the heavens recur in cycles than he set to work to look for law everywhere in nature and with an audacity amounting to hybris to construct a system of the universe' . But their divers speculations had this one feature in common, that the sun‑eating serpents and Olympian string‑pullers were discarded; each theory, however strange and bizarre, was concerned with natural causes.
The sixth century scene evokes the image of an orchestra expectantly tuning up, each player absorbed in his own instrument only, deaf to the caterwaulings of the others. Then there is a dramatic silence, the conductor enters the stage, raps three times with his baton, and harmony emerges from the chaos. The maestro is Pythagoras of Samos, whose influence on the ideas, and thereby on the destiny, of the human race was probably greater than that of any single man before or after him.