Astronomy was one of these. In this science such men as Eratosthenes, Aristarchus, Hipparchus, and Ptolemy were great lights of whom humanity may be proud; and had they been assisted by our modern inventions, they might have earned a fame scarcely eclipsed by that of Kepler and Newton. The old astronomers did little to place this science on a true foundation, but they showed great ingenuity, and discovered some truths which no succeeding age has repudiated. They determined the circumference of the earth by a method identical with that which would be employed by modern astronomers; they ascertained the position of the stars by right ascension and declination; they knew the obliquity of the ecliptic, and determined the place of the sun's apogee as well as its mean motion. Their calculations on the eccentricity of the moon prove that they had a rectilinear trigonometry and tables of chords. They had an approximate knowledge of parallax; they could calculate eclipses of the moon, and use them for the correction of their lunar tables. They understood spherical trigonometry, and determined the motions of the sun and moon, involving an accurate definition of the year and a method of predicting eclipses; they ascertained that the earth was a sphere, and reduced the phenomena of the heavenly bodies to uniform movements of circular orbits. We have settled by physical geography the exact form of the earth, but the ancients arrived at their knowledge by astronomical reasoning. Says Whewell:--
"The reduction of the motions of the sun, moon, and five planets to circular orbits, as was done by Hipparchus, implies deep concentrated thought and scientific abstraction. The theories of eccentrics and epicycles accomplished the end of explaining all the known phenomena. The resolution of the apparent motions of the heavenly bodies into an assemblage of circular motions was a great triumph of genius, and was equivalent to the most recent and improved processes by which modern astronomers deal with such motions."
Astronomy was probably born in Chaldaea as early as the time of Abraham. The glories of the firmament were impressed upon the minds of the rude primitive races with an intensity which we do not feel, with all the triumphs of modern science. The Chaldaean shepherds, as they watched their flocks by night, noted the movements of the planets, and gave names to the more brilliant constellations. Before religious rituals were established, before great superstitions arose, before poetry was sung, before musical instruments were invented, before artists sculptured marble or melted bronze, before coins were stamped, before temples arose, before diseases were healed by the arts of medicine, before commerce was known, those Oriental shepherds counted the anxious hours by the position of certain constellations. Astronomy is therefore the oldest of the ancient sciences, although it remained imperfect for more than four thousand years. The old Assyrians, Egyptians, and Greeks made but few discoveries which are valued by modern astronomers, but they laid the foundation of the science, and ever regarded it as one of the noblest subjects that could stimulate the faculties of man. It was invested with all that was religious and poetical.
The spacious level and unclouded horizon of Chaldaea afforded peculiar facilities of observation; and its pastoral and contemplative inhabitants, uncontaminated by the vices and superstitions of subsequent ages, active-minded and fresh, discovered after a long observation of eclipses--some say extending over nineteen centuries--the cycle of two hundred and twenty-three lunations, which brings back the eclipses in the same order. Having once established their cycle, they laid the foundation for the most sublime of all the sciences. Callisthenes transmitted from Babylon to Aristotle a collection of observations of all the eclipses that preceded the conquests of Alexander, together with the definite knowledge which the Chaldaeans had collected about the motions of the heavenly bodies. Such knowledge was rude and simple, and amounted to little beyond the fact that there were spherical revolutions about an inclined axis, and that the poles pointed always to particular stars. The Egyptians also recorded their observations, from which it would appear that they observed eclipses at least sixteen hundred years before the beginning of our era,--which is not improbable, if the speculations of modern philosophers respecting the age of the world are entitled to credit. The Egyptians discovered by the rising of Sirius that the year consists of three hundred and sixty-five and one-quarter days; and this was their sacred year, in distinction from the civil, which consisted of three hundred and sixty-five days. They also had observed the courses of the planets, and could explain the phenomena of the stations and retrogradations; and it is asserted too that they regarded Mercury and Venus as satellites of the sun. Some have maintained that the obelisks which the Egyptians erected served the purpose of gnomons for determining the obliquity of the ecliptic, the altitude of the pole, and the length of the tropical year. It is thought even that the Pyramids, by the position of their sides toward the cardinal points, attest Egyptian acquaintance with a meridional line. The Chinese boast of having noticed and recorded a series of eclipses extending over a period of thirty-eight hundred and fifty-eight years; and it is probable that they anticipated the Greeks two thousand years in the discovery of the Metonic cycle,--or the cycle of nineteen years, at the end of which time the new moons fall on the same days of the year. The Chinese also determined the obliquity of the ecliptic eleven hundred years before our era. The Hindus at a remote antiquity represented celestial phenomena with considerable exactness, and constructed tables by which the longitude of the sun and moon were determined, and dials to measure time. Bailly thinks that thirty-one hundred and two years before Christ astronomy was cultivated in Siam which hardly yields in accuracy to that which modern science has built on the theory of universal gravitation.
But the Greeks after all were the only people of antiquity who elevated astronomy to the dignity of a science. They however confessed that they derived their earliest knowledge from the Babylonian and Egyptian priests, while the priests of Thebes claimed to be the originators of exact astronomical observations. Diodorus asserts that the Chaldaeans used the Temple of Belus, in the centre of Babylon, for their survey of the heavens. But whether the Babylonians or the Egyptians were the earliest astronomers is of little consequence, although the pedants make it a grave matter of investigation. All we know is that astronomy was cultivated by both Babylonians and Egyptians, and that they made but very limited attainments. They approximated to the truth in reference to the solar year, by observing the equinoxes and solstices and the heliacal rising of particular stars.
The early Greek philosophers who visited Egypt and the East in search of knowledge, found very little to reward their curiosity or industry,--not much beyond preposterous claims to a high antiquity, and to an esoteric wisdom which has not yet been revealed. Plato and Eudoxus spent thirteen years in Heliopolis for the purpose of extracting the scientific knowledge of the Egyptian priests, yet they learned but little beyond the fact that the solar year was a trifle beyond three hundred and sixty-five days. No great names have come down to us from the priests of Babylon or Egypt; no one gained an individual reputation. The Chaldaean and Egyptian priests may have furnished the raw material of observation to the Greeks, but the latter alone possessed the scientific genius by which undigested facts were converted into a symmetrical system. The East never gave valuable knowledge to the West; it gave the tendency to religious mysticism, which in its turn tended to superstition. Instead of astronomy, it gave astrology; instead of science, it gave magic, incantations, and dreams. The Eastern astronomers connected their astronomy with divination from the stars, and made their antiquity reach back to two hundred and seventy thousand years. There were soothsayers in the time of Daniel, and magicians, exorcists, and interpreters of signs. They were not men of scientific research, seeking truth; it was power they sought, by perverting the intellect of the people. The astrology of the East was founded on the principle that a star or constellation presided over the birth of an individual, and that it either portended his fate, or shed a good or bad influence upon his future life. The star which looked upon a child at the hour of his birth was called the "horoscopus," and the peculiar influence of each planet was determined by the astrologers. The superstitions of Egypt and Chaldaea unfortunately spread among both the Greeks and Romans, and these were about all that the Western nations learned from the boastful priests of occult Oriental science. Whatever was known of real value among the ancients is due to the earnest inquiries of the Greeks.
And yet their researches were very unsatisfactory until the time of Hipparchus. The primitive knowledge was almost nothing. The Homeric poems regarded the earth as a circular plain bounded by the heaven, which was a solid vault or hemisphere, with its concavity turned downward. This absurdity was believed until the time of Herodotus, five centuries after; nor was it exploded fully in the time of Aristotle. The sun, moon, and stars were supposed to move upon or with the inner surface of the heavenly hemisphere, and the ocean was thought to gird the earth around as a great belt, into which the heavenly bodies sank at night. Homer believed that the sun arose out of the ocean, ascended the heaven, and again plunged into the ocean, passing under the earth, and producing darkness. The Greeks even personified the sun as a divine charioteer driving his fiery steeds over the steep of heaven, until he bathed them at evening in the western waves. Apollo became the god of the sun, as Diana was the goddess of the moon. But the early Greek inquirers did not attempt to explain how the sun found his way from the west back again to the east; they merely took note of the diurnal course, the alternation of day and night, the number of the seasons, and their regular successions. They found the points of the compass by determining the recurrence of the equinoxes and solstices; but they had no conception of the ecliptic,--of that great circle in the heaven formed by the sun's annual course,--and of its obliquity when compared with our equator. Like the Egyptians and Babylonians, the Greeks ascertained the length of the year to be three hundred and sixty-five days; but perfect accuracy was lacking, for want of scientific instruments and of recorded observations of the heavenly bodies. The Greeks had not even a common chronological era for the designation of years. Herodotus informs us that the Trojan War preceded his time by eight hundred years: he merely states the interval between the event in question and his own time; he had certain data for distant periods. The Greeks reckoned dates from the Trojan War, and the Romans from the building of their city. The Greeks also divided the year into twelve months, and introduced the intercalary circle of eight years, although the Romans disused it afterward, until the calendar was reformed by Julius Caesar. Thus there was no scientific astronomical knowledge worth mentioning among the primitive Greeks.
Immense research and learning have been expended by modern critics to show the state of scientific astronomy among the Greeks. I am amazed equally at the amount of research and its comparative worthlessness; for what addition to science can be made by an enumeration of the puerilities and errors of the Greeks, and how wasted and pedantic the learning which ransacks all antiquity to prove that the Greeks adopted this or that absurdity![[1]]