|Born||Early 5th century BCE
Abdera or Miletus
|Died||5th century BCE
|School||Pre-Socratic philosophy: Atomism, Materialism|
Leucippus or Leukippos (Greek: Λεύκιππος, first half of 5th century BC) was the first Greek to develop the theory of atomism — the idea that everything is composed entirely of various imperishable, indivisible elements called atoms — which was elaborated in far greater detail by his pupil and successor, Democritus.
He was born very probably in Miletus  and little probably in Abdera. Not at all probable Elea (Italy), improperly quoted by Diogenes Laertius (Vitae philosophorumIX, 30 ss,) and Simplicius of Cilicia (Physica, 28, 4) 
Leucippus was a shadowy figure, as his dates are not recorded and he is often mentioned in conjunction with his more well-known pupil Democritus, who yet moves away replacing indeterminism with determinism as ontological cause of atoms movement. It is therefore difficult to determine which contributions come from Democritus or from those of Leucippus because those of this one met in the Trasyllus catalogue named Corpus Democriteum. Trasyllus of Alexandria, an astrologer and writer living under Tiberius empire (14-37 a.C) compiled a list of writings traditionally attribuited to Democritus as famous atomist in total oblivion of Leucippus, his teacher and surely not less important of him.
Leucippus was an Ionic (came from Eastern Greece, at present Turkey) as Anaxagoras, contemporary of Zeno of Elea and Empedocles (both of Western Greece, at present Italy). Of the Ionian school of naturalistic philosophy ((Thales],Anaximandrus, Anaximenes, he was nterested to reality and noto ideality as italic Eleates. The legend about the influence of Zeno is totally false, as modern studies established, also because the ontological conception of the being by the Eleates is static, monistic and deterministic, while that one of Leucippus is dynamic, pluralistic and indeterministic.
Around 440 B.C. or 430 B.C. Leucippus founded a school at Abdera, which his pupil, Democritus, was closely associated with. His fame was so completely overshadowed by that of Democritus, who systematized his views on atoms, that Epicurus doubted his very existence, according to Diogenes Laertius x. 7.
However, Aristotle and Theophrastus explicitly credit Leucippus with the invention of Atomism. Leucippus agreed with the Eleatic argument that true being does not admit of vacuum, and there can be no movement in the absence of vacuum. Leucippus contended that since movement exists, there has to be vacuum. However, he concludes that vacuum is identified with non-being, since it cannot really be. Leucippus differed from the Eleatics in not being encumbered by the conceptual intermingling of being and non-being. Plato made the necessary distinction between grades of being and types of negation.
The most famous among Leucippus' lost works were titled Megas Diakosmos (The Great Order of the Universe or The great world-system) and Peri Nou (On mind).
Hermann Diels - Walter Kranz, Die Fragmente der Vorsokratiker (Berlin 1931), A 67 24}}
A.A. Long (ed.), The Cambridge Companion to Early Greek Philosophy (pgs. xxiii, 185)
Diels-Kranz, Die Fragmente der Vorsokratiker [I] 67A
Diogenes Laertius, Diogenes Lartius: Lives of Eminent Philosophers, IX.30-33
LEUCIPPUS, Greek philosopher, born at Miletus (or Elea), founder of the Atomistic theory, contemporary of Zeno, Empedocles and Anaxagoras. His fame was so completely overshadowed by that of Democritus, who subsequently developed the theory into a system, that his very existence was denied by Epicurus (Diog. Laert. x. 7), followed in modern times by E. Rohde. Epicurus, however, distinguishes Leucippus from Democritus, and Aristotle and Theophrastus expressly credit him with the invention of Atomism. There seems, therefore, no reason to doubt his existence, although nothing is known of his life, and even his birthplace is uncertain. Between Leucippus and Democritus there is an interval of at least forty years; accordingly, while the beginnings of Atomism are closely connected with the doctrines of the Eleatics, the system as developed by Democritus is conditioned by the sophistical views of his time, especially those of Protagoras. While Leucippus's notion of Being agreed generally with that of the Eleatics, he postulated its plurality (atoms) and motion, and the reality of not-Being (the void) in which his atoms moved.
Species: L. baeri - L. chionogaster - L. chlorocercus - L. fallax - L. hypostictus - L. taczanowskii - L. viridicauda
Leucippus Bonaparte, 1850
Leucippus or Leukippos (Greek: Λεύκιππος, first half of 5th century BC) was among the earliest philosophers of atomism, the idea that everything is made up of many imperishable, indivisible elements called atoms. He was born at Miletus or Abdera