Know thyself

"Know thyself" (Greek: Γνῶθι σεαυτόν, gnōthi seauton) is a philosophical Delphic maxim which was inscribed upon the Temple of Apollo in the ancient Greek precinct of Delphi. The best-known of the Delphic maxims, it has been quoted and analyzed by numerous authors throughout history, and has been applied in many ways. Although traditionally attributed to the Seven Sages of Greece, or to the god Apollo himself, the inscription likely had its origin in a popular proverb.

Ion of Chios makes the earliest explicit allusion to the maxim in a fragment dating to the 5th century BC, though the philosopher Heraclitus, active towards the end of the previous century, may also have made reference to the maxim in his works. The principal meaning of the phrase in its original application was "know your limits" – either in the sense of knowing the extent of one's abilities, knowing one's place in the world, or knowing oneself to be mortal. In the 4th century BC, however, the maxim was drastically reinterpreted by Plato, who understood it to mean, broadly speaking, "know your soul".