His ideas of the solar orb were extremely erroneous; alleging, according to different authors, various uncertain positions respecting the materials of which that planet is composed: one says, _he_ said it was a vast mass of fire; another states _his_ opinion, that it was red-hot iron; and a third, that it was of stone. He taught that the comets are an assemblage of planets; that winds are produced in consequence of highly rarified air; that thunder and lightning are a collision of clouds; earthquakes, by subterraneous air forcing its passage upwards; that the moon is inhabited, &c. This philosopher removed his school from Miletus to Athens, which was thenceforth the grand seat of all learning. He had taught there for thirty years, when he was prosecuted for his philosophical opinions, particularly for his just ideas relative to the Deity, and condemned to death. When sentence was pronounced, he said:--“It is long since Nature condemned me to that.” However, according to the laws of Athens, he was permitted an appeal to the people, in which his scholar, the immortal Pericles, saved his life by his eloquence. His sentence of death was changed into banishment. Whilst in prison he determined exactly the proportion of the circumference of the circle to its diameter, denominated “squaring the circle.” He died at Lampsacus. Archelaus, his scholar, was the preceptor of the divine Socrates. Pythagoras was another scholar of Thales. The place of his nativity is uncertain; but having settled in the island of Samos, he is generally reckoned of that place. He travelled in search of knowledge through Phœnicia, Chaldea, Egypt, and India; however, meeting with little encouragement on his return to Samos, he passed over to Italy, in the time of Tarquin the Proud, and opened a school at Croto, a city in the Gulf of Tarentum, where he had a number of students, and gained much reputation. His pupils were obliged to listen in silence for at least two years; if talkative, longer; sometimes, for five years, before they were permitted to ask him any questions; for which time they were _mathematicoi_, because they were set to study geometry, dialling, music, and other high sciences, called by the Greeks _mathemata_. But the name of _mathematici_ was commonly applied to those who cultivated the stellary science, and who predicted the fortunes of men, by observing the stars under which they were born. This luminary of science first assumed the appellation of _philosopher_; before him, those whose pursuits have now that title, were called sages or wise men; he was the founder of the sect called the Italic. He was so much honoured whilst living, and his memory honoured when dead, by the Romans, that they attributed to him the learning of Numa, who lived much earlier. About the year of the city 411, the Delphian oracle having directed the Romans to erect statues to the bravest and wisest of the Greeks, they conferred that honour upon Alcibiades and Pythagoras.