Of all the achievements of Thales his prediction of the eclipse of the sun (May 28, 585) is that which caused the greatest amazement, although its scientific significance is the most trifling of any. For, as the history of astronomy proves beyond controversy, Thales and his whole generation lacked the rudiments of knowledge necessary for the calculation of eclipses, and had not the faintest notion of how they came about. Hence he can only have employed according to a fixed method some such formula as the Chaldeans had gained from empiric observation in calculating their eclipse period of eighteen years and eleven days (Saros). The rule only suffices for approximate predictions. As a matter of fact, Herodotus, the earliest witness to this event, states that Thales allowed a margin of a whole year for the occurrence of the eclipse.
Thales himself left no written works, and this Ionic Historia first emerges into the full light of day with Anaximander of Miletus, who founded the Ionic school about a generation later. In him the three forces are strongly marked and defined—first the scientific spirit, which impelled him to give visible expression to the geographical ideas of his countrymen by means of a map of the earth’s surface, and to make a systematic description of the heavens with the stationary and revolving celestial bodies. With him originated the conception of the constellations as a system of spheres rotating through and within one another, and it was his mathematical imagination that led him to assume the existence of certain fixed intervals between the revolving spheres, arbitrarily determined as to number, but expressing in their proportion the idea of harmony.
Here we have the germ of the speculations of Pythagoras, on which, as is well known, the laws of Copernicus and Kepler are founded. The vein of poetry in the Ionian character is manifest not only in this intuitive perception but in the aptness of his imagery, when he calls these spheres “chariot-wheels,” from the rim of which the fiery flames of the sun, moon, etc., start out like felloes. The scientific element in his system is evident in the manner in which he follows out biologically the idea of Thales concerning water. If all things have at one time been water, then organisms cannot originally have been created as land animals. Hence man, who now comes into the world utterly helpless, has been gradually evolved from pisciform creatures—the first germ of Darwinism.
Lastly the pessimistic mysticism which had lately arisen is clearly manifest in him. When he regards the origin of all individual existences as a wrong committed by them in separating themselves from the All-One, we can only understand him by referring to Orphic religious ideas, in which birth is looked upon as a decline and fall from the blissful seats of the gods and earthly life is represented as a vale of misery. Death is consequently the penalty which the individual pays for his presumption, whether the individual be a man or a celestial body. For the earth and all other Cosmoi are doomed to extinction in an “Infinite” which corresponds to the ancient idea of Chaos, and, like that, is not conceived of as a vacuum but as matter in an undefined form. This alternation of creation and annihilation, this perpetual motion, anticipates the eternal flux of Heraclitus of Ephesus, who at the end of the sixth century and the beginning of the fifth, transformed the teaching of Anaximander into keener dialectics.
In comparison with this Ephesian thinker the successors of Anaximander at Miletus and whatsoever following they had down to the end of the fifth century sink into total obscurity. Before turning our attention to Heraclitus, however, we must first consider the man who transplanted the Ionic Historia from Ionia to Italy and there elaborated both the scientific and mystic side of it with marvellous assiduity—that is, Pythagoras.
Pythagoras left Samos about the year 530, and turned his steps towards Croton in lower Italy, where he found virgin soil for his labours. The mathematical foundation upon which the Ionic school is based attains an excessive predominance with Pythagoras. Epoch-making maxims are associated with his name, and probably not without good reason. But the speculative tendency of the Ionic mind prompted him to set up number itself as a principle; the Infinite of Anaximander being conceived of arithmetically as the Uneven, i.e., that which cannot be divided by two. Since the Even and Uneven alone co-exist, the sacred Three is compounded of Unity and Duality, as is also the Four (tetraktys), the root of Being. By simply adding these first four numbers together the Decas (1 + 2 + 3 + 4 = 10) is obtained. The cosmos is made to consist of ten celestial bodies, corresponding to this Decas, by the addition of the heaven of the fixed stars as an outermost crust, and the earth and the “anti-earth” (antichthon) containing the central fire, at the heart of it. The earth and other stars moved round this centre, and here we have the first glimpse of the modern conception which explains the apparent diurnal motion of the heavens by the rotation of the earth. This rudimentary idea, as elaborated by later Pythagoreans, and particularly by Aristarchus of Samos in the Alexandrine period, constitutes the first starting-point we can assign to the Copernican system of the universe.
Pythagoras made the astounding discovery that the harmonic intervals of the seven-stringed lyre can be reduced to simple rational proportions (the octave = 1:2, the fifth 2:3, the fourth 3:4, the whole tone 8:9). He then sought for a like scheme in the harmony of the spheres, and, as the geometric habit of the Greek mind converted these arithmetical relations into lines and planes, the whole process by which the universe came into existence seemed to be a sum in arithmetic.
The strong tinge of mysticism which Pythagoras had brought with him from the Orphic influences of his native land to his new home in Italy served as a wholesome corrective to this exaggerated rationalism. Every religious sect thrives better in a colony than in the mother-country, as is demonstrated in the case of William Penn and many others. The aristocratic and religious league which Pythagoras founded at Croton prospered mightily, and presently the whole of lower Italy and Sicily was covered with branches of the order. Its religious ideas, particularly that of the transmigration of souls, were not new, although they have been claimed as peculiarly Pythagorean. Orphic mysticism had adopted in precisely the same fashion the notion of the fall of the spirit and its purification by transmigrations of all kinds into the bodies of men and animals. But the earnestness with which noble-minded men lived conformably to these ideas in matters of practice and brought them into connection with the results of scientific research strongly impressed the ancient world; and the close freemasonry which linked Pythagoreans from every quarter with one another set forth an ideal of manly friendship which served as a model for the institution of the Academy and similar philosophic societies.
But the too strongly marked political complexion of these Pythagorean societies contained the seed of their destruction. At the end of the sixth century and the beginning of the fifth the aristocratic principle was everywhere on the decline, and in Italy itself the Pythagoreans were attacked on democratic grounds by Xenophanes of Colophon, who ridiculed the aristocratic physical sports in which even distinguished Pythagoreans (such as Milo) indulged, and vaunted the intellectual sport of his own Sophia. The said wisdom, it must be confessed, was of a negative rather than a positive character.
Xenophanes attacked Homer, the Bible of the ancients, in verses of fierce satire, showing the gods as there depicted to be examples of every kind of immorality. By the unparalleled vigour with which he transferred the monistic tendency of Ionic rationalism to the religious problem, he, first of all Greeks, originated the monotheistic conception of the Deity, which none of the later philosophers ventured to maintain with such unflinching boldness in face of the polytheism of the vulgar herd. To the aristocratic submission to authority in matters of belief required by the Pythagoreans this democratic philosopher opposed the prerogative of doubt, and he has consequently been lauded by the sceptics of all ages as their standard-bearer. At this stage of physical observation, indeed, doubt sets in concerning natural objects. Xenophanes discovers that the rainbow is an optical illusion. He promptly generalises in his scepticism; the sun and the other stars are nothing but fiery exhalations. This assumption will lead to further results among his Eleatic friends.