Vitae philosophorum

The generation of man proceeded from the sun as first cause; heat and cold, of which all things consist, surpass the sun itself. Again he held that soul and mind are one and the same, as Theophrastus mentions in his Physics, where he is setting forth the tenets of almost all the schools. He divided his philosophy into two parts dealing the one with truth, the other with opinion. Hence he somewhere says[*](Fr. 1. 28 D.):

Thou must needs learn all things, as well the unshakeable heart of well-rounded truth as the opinions of mortals in which there is no sure trust.[*](The text of Parmenides had suffered in the course of time. Here Laertius, like Sextus Empiricus and Plutarch, read εὐπειθέος ἀτρεκὲς; Proclus, two centuries later, εὐφεγγέος; but Simplicius, on De caelo, enables us to go behind our author by citing (as he no doubt would have wished to do) the better reading.)

Our philosopher too commits his doctrines to verse just as did Hesiod, Xenophanes and Empedocles. He made reason the standard and pronounced sensations to be inexact. At all events his words are[*](Fr. 1. 34 D.):

And let not long-practised wont force thee to tread this path, to be governed by an aimless eye, an echoing ear and a tongue, but do thou with understanding bring the muchcontested issue to decision.