The Thought of Thales Summarized by Diogenes Laertius

Author: Diogenes Laertius


Diogenes Laertius

I. Thales, then, as Herodotus and Duris and Democritus say, was the son of Euxamius and Cleobule; of the family of the Thelidae, who are Phoenicians by descent, among the most noble of all the descendants of Cadmus and Agenor, as Plato testifies. And he was the first man to whom the name of Wise was given, when Damasius was Archon at Athens, in whose time also the seven wise men had that title given to them, as Demetrius Phalereus records in his Catalogue of the Archons. He was enrolled as a citizen at Miletus when he came thither with Neleus, who had been banished from Phoenicia; but a more common statement is that he was a native Milesian, of noble extraction.

II. After having been immersed in state affairs he applied himself to speculations in natural philosophy; though, as some people state, he left no writings behind him, for the book on Naval Astronomy, which is attributed to him is said in reality to be the work of Focus the Samian. But Callimachus was aware that he was the discoverer of the Lesser Bear; for in his Iambics he speaks of him thus:

And, he, ’tis said, did first compute the stars
Which beam in Charles’s wain, and guide the bark
Of the Phoenician sailor o’er the sea.

According to others he wrote two books, and no more, about the solstice and the equinox; thinking that everything else was easily to be comprehended. According to other statements, he is said to have been the first who studied astronomy, and who foretold the eclipses and motions of the sun, as Eudemus relates in his history of the discoveries made in astronomy; on which account Xenophanes and Herodotus praise him greatly; and Heraclitus and Democritus confirm this statement.

III. Some again (one of whom is Chaerilus the poet) say that he was the first person who affirmed that the souls of men were immortal; and he was the first person, too, who discovered the path of the sun from one end of the ecliptic to the other; and who, as one account tells us, defined the magnitude of the sun as being seven hundred and twenty times as great as that of the moon. He was also the first person who called the last day of the month the thirtieth. And likewise the first to converse about natural philosophy, as some say. But Aristotle and Hippias say that he attributed souls also to lifeless things, forming his conjecture from the nature of the magnet, and of amber.

VI. He asserted water to be the principle of all things, and that the world had life, and was full of demons; they say, too, that he was the original definer of the seasons of the year, and that it was he who divided the year into three hundred and sixty-five days. And he never had any teacher except during the time that he went to Egypt, and associated with the priests. Hieronymus also says that he measured the Pyramids: watching their shadow, and calculating when they were of the same size as that was. He lived with Thrasybulus the tyrant of Miletus, as we are informed by Minyas.

IX. These are quoted as some of his lines:—

It is not many words that real wisdom proves;
     Breathe rather one wise thought,
     Select one worthy object,
So shall you best the endless prate of silly men reprove.—

And the following are quoted as saying of his:—"God is the most ancient of all things, for he had no birth: the world is the most beautiful of things, for it is the work of God; place is the greatest of things, for it contains all things: intellect is the swiftest of things, for it runs through everything: necessity is the strongest of things, for it rules everything: time is the wisest of things, for it finds out everything."

He said also that there was no difference between life and death. "Why, then," said some one to him, "do not you die?" . . . "Because," said he, "it does make no difference." A man asked him which was made first, night or day, and he replied, "Night was made first by one day." Another man asked him whether a man who did wrong, could escape the notice of the gods. "No, not even if he thinks wrong," said he. An adulterer inquired of him whether he should swear that he had not committed adultery. "Perjury," said he, "is no worse than adultery." When he was asked what was very difficult, he said, "To know one’s self." And what was easy, "To advise another." What was most pleasant? "To be successful." To the question, "What is the divinity?" he replied, "That which has neither beginning nor end." When asked what hard thing he had seen, he said, "An old man a tyrant." When the question was put to him how a man might most easily endure misfortune, he said, "If he saw his enemies more unfortunate still." When asked how men might live most virtuously and most justly, he said, "If we never do ourselves what we blame in others." To the question, "Who was happy?" he made answer, "He who is healthy in his body, easy in his circumstances, and well-instructed as to his mind." He said that men ought to remember those friends who were absent as well as those who were present, and not to care about adorning their faces, but to be beautified by their studies. "Do not," said he, "get rich by evil actions, and let not any one ever be able to reproach you with speaking against those who partake of your friendship. All the assistance that you give to your parents, the same you have a right to expect from your children." He said that the reason of the Nile overflowing was, that its streams were beaten back by the Etesian winds blowing in a contrary direction.—Diogenes Laertius.

Translation Of C. D. Yonge.

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Chicago: Diogenes Laertius, The Thought of Thales Summarized by Diogenes Laertius in The Library of Original Sources, ed. Oliver J. Thatcher (Milwaukee, WI: University Research Extension Co., 1907), 138–140. Original Sources, accessed February 21, 2024,

MLA: Laertius, Diogenes. The Thought of Thales Summarized by Diogenes Laertius, in The Library of Original Sources, edited by Oliver J. Thatcher, Vol. 2, Milwaukee, WI, University Research Extension Co., 1907, pp. 138–140. Original Sources. 21 Feb. 2024.

Harvard: Laertius, D, The Thought of Thales Summarized by Diogenes Laertius. cited in 1907, The Library of Original Sources, ed. , University Research Extension Co., Milwaukee, WI, pp.138–140. Original Sources, retrieved 21 February 2024, from