« AnteriorContinuar »
eclipsed by that of Ptolemy, A.D. 138, the author of the great work“Syntaxis,” or the mathematical con- The writings struction of the heavens—a work fully deserving of Ptolemy. the epithet which has been bestowed upon it, “ a noble exposition of the mathematical theory of epicycles and eccentrics.” It was translated by the Arabians after the Mohammedan conquest of Egypt; and, under the title of Almagest, was received by them as the highest authority on the mechanism and phenomena of the universe. It maintained its ground in Europe in the same eminent position for nearly fifteen hundred years, justifying the encomium of Synesius on the institution which gave it birth, “the divine school of Alexandria.” The Almagest commences with the doctrine that the earth is
His great globular and fixed in space; it describes the work: the construction of a table of chords and instruments construction for observing the solstices, and deduces the of the heavens. obliquity of the ecliptic. It finds terrestrial latitudes by the gnomon; describes climates; shows how ordinary may be converted into sidereal time; gives reasons for preferring the tropical to the sidereal year; furnishes the solar theory on the principle of the sun's orbit being a simple eccentric; explains the equation of time; advances to the discussion of the motions of the moon; treats of the first inequality, of her eclipses, and the motion of the node. It then gives Ptolemy's own great discovery—that which has made his name immortal—the discovery of the moon's evection or second inequality, reducing it to the epicyclic theory. It attempts the determination of the distances of the sun and moon from the earth, with, however, only partial success, since it makes the sun's distance but ono twentieth of the real amount. It considers the precession of the equinoxes, the discovery of Hipparchus, the full period for which is twenty-five thousand years. It gives a catalogue of 1,022 stars; treats of the nature of the Milky Way; and discusses, in the most masterly manner, the motions of the planets. This point constitutes Ptolemy's second claim to scientific fame. His determination of the planetary orbits was accomplished by comparing his own observations with those of former astronomers, especially with those of Timochares on Venus.
To Ptolemy we are also indebted for a work on Geography used in European schools as late as the fifteenth century. The known world to him was from the Canary Islands
eastward to China, and from the equator northphy. ward to Caledonia. His maps, however, are very erroneous ; for, in the attempt to make them correspond to the spherical figure of the earth, the longitudes are too much to the east; the Mediterranean Sea is twenty degrees too long. Ptolemy's determinations are, therefore, inferior in accuracy to those of his illustrious predecessor Eratosthenes, who made the distance from the sacred promontory in Spain to the eastern mouth of the Ganges to be seventy thousand stadia. Ptolemy also wrote on Optics, the Planisphere, and Astrology. It is not often given to an author to endure for so many ages; perhaps, indeed, few deserve it. The mechanism of the heavens, from his point of view, has however, been greatly misunderstood. Neither he nor Hipparchus ever intended that theory as anything more than a geometrical fiction. It is not to be regarded as a representation of the actual celestial motions. And, as might be expected, for such is the destiny of all unreal abstractions, the theory kept advancing in complexity as facts accumulated, and was on the point of becoming altogether unmanageable, when it was supplanted by the theory of universal gravitation, which has ever exhibited the inalienable attribute of a true theory-affording an explanation of every new fact as soon as it was discovered, without requiring to be burdened with new provisions, and prophetically foretelling phenemona which had not as yet been observed.
From the time of the Ptolemies the scientific spirit of the Alexandrian school declined; for though such mathematicians as Theodosius, whose work on Spherical Geometry was greatly valued by the Arab geometers; and
Pappus, whose mathematical collections, in eight Alexandrian books, still for the most part remain ; and Theon, gecmeters.
doubly celebrated for his geometrical attainments, and as being the father of the unfortunate Hypatia, A.D. 415, lived in the next three centuries, they were not men like their great predecessors. That mental strength which gives birth to original discovery had passed away.
The commentator had succeeded to the philosopher. No new development illustrated the physical sciences; they were destined long to remain stationary. Mechanics could boast of no trophy like the proposition of Archimedes on the equilibrium of the lever; no new and exact ideas like those of the same great man on statical and hydrostatical pressure; no novel and clear views like those developed in his treatise on floating bodies; no mechanical invention like the first of all steam-engines—that of Hero. Natural Philosophy had come to a stop. Its great, and hitherto successfully cultivated department, Astronomy, exhibited no farther advance.
Men were content with Decline of the what had been done, and continued to amuse Greek age of themselves with reconciling the celestial phenomena to a combination of equable circular motions. To what are we to attribute this pause ? Something had occurred to enervate the spirit of science. A gloom had settled on the Museum.
There is no difficulty in giving an explanation of this unfortunate condition. Greek intellectual life had passed the period of its maturity, and was entering on old age. Moreover, the talent which might have been devoted to the service of science was in part allured to another pursuit, and in part repressed. Alexandria had sapped Athens, and in her turn Alexandria was sapped by Rome. Causes of that From metropolitan pre-eminence she had sunk to decline. be a mere provincial town. The great prizes of life were not so likely to be met with in such a declining city as in Italy or, subsequently, in Constantinople. Whatever affected these chief centres of Roman activity, necessarily influenced her; but, such is the fate of the conquered, she must await their decisions. In the very institutions by which she had once been glorified, success could only be attained by a conformity to the manner of thinking fashionable in the imperial metropolis, and the best that could be done was to seek distinction in the path so marked out. Yet even with all this restraint Alexandria asserted her intellectual power, leaving an indelible impress on the new theology of her conquerors. During three centuries the intellectual atmosphere of the Roman empire had been changing. Men were unable to resist the steadily increasing
pressure. Tranquillity could only be secured by passiveness. Things had come to such a state that the thinking of men was to be done for them by others, or, if they thought at all, it must be in accordance with a prescribed formula or rule. Greek intellect was passing into decrepitude, and the moral condition of the European world was ir antagonism to scientific progress.
THE GREEK AGE OF INTELLECTUAL DECREPITUDE.
THE DEATH OF GREEK PHILOSOPHY,
Decline of Greek Philosophy: it becomes Retrospective, and in Philo
the Jew and Apollonius of Tyana leans on Inspiration, Mysticism,
Miracles. NEO-PLATONISM founded by Ammonius Saccas, followed by Plotinus, Porphyry, Iamblicus, Proclus.- The Alexandrian Trinity.--Ecstasy.
-Alliance with Magic, Necromancy. The Emperor Justinian closes the philosophical Schools. Summary of Greek Philosophy.--Its four Problems: 1. Origin of the
World ; 2. Nature of the Soul ; 3. Existence of God; 4. Criterion of Truth. --Solution of these Problems in the Age
of Inquiry-in that of Faith-in that of Reason-in that of Decrepitude. Determination of the Law of Variation of Greek Opinion. — The
Development of Nutional Intellect is the same as that of Individual. Determination of the final Conclusions of Greek Philosophy as to God,
the World, the Soul, the Criterion of Truth. — Illustrations and Criticisms on each of these Points.
In this chapter it is a melancholy picture that I have to present the old age and death of Greek philo- Decline of sophy. The strong man of Aristotelism and Greek puiloStoicism is sinking into the superannuated sophy. dotard; he is settling
“ Into the lean and slipper'd pantaloon,
With spectacles on nose and pouch on side;