Melissus of Samos, Greek philosopher of the Eleatic School, was born probably not later than 470 BC.
According to Diogenes Laėrtius, ix. 24, he was not only a thinker, but also a political leader in his native town, and was in command of the fleet which defeated the Athenians in 442. The same authority says he was a pupil of Parmenides and of Heraclitus, but the statement is improbable, owing to discrepancy in dates.
His works, fragments of which are preserved by Simplicius and attested by the evidence of Aristotle, are devoted to the defence of Parmenides' doctrine. They were written in Ionic and consist of long series of argument. Being, he says, is eternal. It cannot have had a beginning because it cannot have begun from not-being (cf. ex nihilo nihil), nor from being. It cannot suffer destruction; it is impossible for being to become not being, and if it became another being, there would be no destruction.
According to Simplicius (Physika, f. 22b), he differed here from Parmenides in distinguishing being and absolute being. He goes on to show that eternal being must also be unlimited in magnitude, and, therefore, one and unchangeable. Any change whether from internal or external source, he says, is unthinkable; the One is unvarying in quantity and in kind. There can be no division inside this unity, for any such division implies space or void; but void is nothing, and, therefore, is not. It follows further that being is incorporeal, inasmuch as all body has size and parts.
The fundamental difficulty underlying this logic is the paradox more clearly expressed by Zeno of Elea and to a large extent represented in almost all modern discussion, namely that the evidence of the senses contradicts the intellect. Abstract argument has shown that change in the unity is impossible; yet the senses tell us that hot becomes cold, hard becomes soft, the living dies, and so on. From a comparison of Melissus with Zeno, it appears that the spirit of dialectic was already tentatively at work, though it was not conscious of its own power.
Neither Melissus nor Zeno seems to have observed that the application of these destructive methods struck at the root not only of multiplicity but also of the One whose existence they maintained. The weapons which they forged in the interests of Parmenides were to be used with equal effect against themselves.
See Ritter and Preller, ~ 159-166; Brandis, Commentationum eleaticarum, pt. 1, p. 185; Mullach, Aristotelis de Melisso, Xenophane Gorgia; Pabst, De Melissi fragmentis (Bonn, 1889), and histories of philosophy.