(1) BIOGRAPHIA PHILOSOPHICA; Or, a fuccinct ACCOUNT of The LIVES of the most eminent PHILOSoPHERS and MATHEMATICIANS, from the highest Antiquity to the present Time. IN WHICH The Places of their Birth; their peculiar Genius, and Manner of Study; their Travels for Improvement; the particular Branches of mathematical or philofophical Science in which they excelled; the Inventions, and Discoveries they made, and the Books they publifhed on the various Subjects of Natural History, Philofophy, and the Mathematics, will be methodically related, and digefted according to the Order of Time in which they lived. The LIFE of THALES the MILESIAN. HALES was born, as the beft Writers agree, in fome Part of the 35th Olympiad, flourished in the 50th, and died about the 58th; the Interval between his Birth and public Appearance in Greece, was paffed in Study, and Travels in various Parts of Afia, and into Egypt; in the former he acquired his firft Infight into Aftronomy, and, in the latter, his first Acquaintance with Geometry, Myftical Divinity, and Natural Knowledge. Having finished his Studies abroad, he returned to his Native City, Miletus, and transported the Stock of Learning he had acquired into his own. Country. There are not any particular Circumftances mentioned in hist History respecting fignificant Occurrencies in his Travels, other than the Favour he met with from Amafis King of Egypt, which Favour he loft by being too free in his Opinions concerning Kings; was, by fuch Freedom, obliged to leave the Country; which was the probable Caufe of his returning, at that Time, to Miletus. In Miletus he lived for fome Time as private as poffible, devoted to Study and Contemplation, and in inftructing some few in the Learning he had acquired. Thefe were Anaximander and Anaximines, both Natives of Miletus; and afterwards Pythagoras, of what Country unknown, but ufually called of Samos, fa famed, as the Conftitutor of the Italic Sect, and who affiduously pursued his Master's Steps, both in his Studies, and in his Travels. Thales, in this his Retirement, was courted by many, but cautiously avoided either attending, or receiving any Favours from them. He was often vifited by Solon, and is faid to have taken great Pleasure in the Converfation of Thrafybulus, whose excellent Wit caused our Philofopher to forget that he was Tyrant of Miletus. There flourished, at the fame Time with him, fix others, diftinguished for their fingular Wisdom by their Morals, Rules, and Practice; but the Epithet of Wife was given to Thales for his fpeculative Learning. Laertius, and with him various other Writers, agree, that he was the Father of the Greek Philofophy, the firft that made any Researches into natural Knowledge, or Enquiry into Mathematics. His Doctrine was, that Water, Moisture, or Humidity is the first Principle of natural Bodies, whereof they confift, and whereinto they refolve; and that God is the Mind, which formed all Things of Water. Of the World, he taught, there was but one, and that made by God; that it is difpofed in due and regular Order, and that God animates the whole. In Geometry he is faid to have been an Inventor, as well as an Improver; a Science that had its Birth by Neceffity in Ægypt, where where Thales acquired his primary Inftruction, as Commerce first gave Being, by the like Neceffity, to Numbers. He gave the first Light into the Knowledge of scalenous, and other Triangles, many of which Euclid has digested into his Elements; but that for which he is more particularly celebrated, as being, according to Laertius, his Invention, is what now appears as the 47th Propofition of Euclid, That the Sums of the Squares of the two lesser Sides of a right angled Triangle is equal to the Square of the greater Side; which is, however, difputed as the Invention of his Difciple Pythagoras. But all the Writers agree, that he was the firft, even in Ægypt, who took the Height of the Pyramids by the Shadow, in the Manner the fame is now ufually effected, and therefore needs not any Illuftration. As an Aftronomer, he divided the celeftial Spheres into five Circles, or Zones, the Artic, the Summer Tropic, the Equator, the Winter Tropic, and the Antartic Circle, placing the Zodiac under the three middle Circles, touching them all as it paffes, and each of them cut in right Angles by the Meridian, that extendeth from Pole to Pole: Which have unjustly been ascribed to more modern Discoveries. He first observed the apparent Diameter of the Sun, which he concluded to be the 720th Part of the Circle or Zodiac, which he appears annually to defcribe about the Earth, which is divided into 360 Degrees; and firft difcovered the Conftellation of the leffer Bear. He likewife firft obferved the Nature and Course of Eclipfes, and calculated them to an Exactnefs; one in particular, about the 50th Olympiad, memorably recorded by Herodotus, as it happened on a Day of Battle between the Medes, and Lydians, which, Laertes fays, he had foretold to the Ionians. And the fame Author informs us he divided the Year into 365 Days; but this Division he seeins to have had from the Egyptians. Plutarch de placit. Philos, not only confirms his general Knowledge of Eclipfes, but that his Doctrine was, that an Eclipfe of the Sun is occafioned by the Intervention of the Moon, as may be feen in a Bason of Water, or Looking-glass; and that an Eclipse of the Moon is caused by the Intervention of the Earth. B 2 Lib. 1. Def. 17.- Prop. 5.-Prop. 15. Id. 26. The The Writers of his Life agree, that he was addicted to judicial Aftrology; and Tully thinks there is something in that Science, and of his Acquaintance there-with, which he aims to confirm by the following Story: That Thales being upbraided for his Poverty, resulting from the Study of Science, and foreseeing by his Skill in Aftrology, there would be a Plenty of Olives that Year, he purchased all the Gardens about Miletus and Chios, and thus having acquired a Monopoly, disposed of them again at high Prices, and then told his Neighbours, that it was very eafy for Men of Learning to be rich if they chose it, but that Wealth was not their Aim. Laertius, and fome others, agree with Tully in the Notion of this being an Aftrological Prediction, which is far from being a clear Point: It is fufficient, that he was capable of making a good Judgment of the approaching Seafon, and that it would be fuch a Season, as wherein Olives are usually most plentiful. This, however, fufficiently evinces, that he had more worldly Wit than his Neighbours conceived, when he thought proper to employ it; as is the Cafe of most studious Men, when they turn their Attention that Way, and affect the Object, as by Study they acquire a Sagacity and Penetration not common to the In-attentive: But, as Self-intereft is the ruling Paffion of our Natures, Men turned only to the Attainment of Wealth, will, with fome Reafon, fmile at those who reduce themfelves to Poverty, in order to make others learned. It is a fufficient Illuftration of the Wisdom of Thales, that he was the Inventor, or Improver, in many Branches of useful Knowledge; and whether right or wrong in his Contempt of Wealth, his Sagacity in other Refpects fuperior to most Men. His Morals were as juft, as his Mathematics well grounded, and his Judgement in civil Affairs equal to either; so that his Knowledge was as general, as the Good of Mankind his Care; and as we have given a brief Account of his Skill in Science, it may not be amifs to give here a concife Taste of his Morals, fummed up in a few Lines. Fear e'er thou fin, thyself, tho' none be nigh, Let |