Presocratic philosophers, collectively referred to as Presocratics, were the first Greek philosophers as well as the first philosophers of the Western tradition, also considered to be the first empirical scientists. The term "Presocratics" might be a bit misleading – some of the thinkers were Socrates' contemporaries rather than his seniors.
Some of this philosophers were the Milesian Thales of Miletus, Anaximander of Miletus and Anaximenes of Miletus, Xenophanes of Colophon and Heraclitus of Ephesus, Parmenides of Elea, his pupil Zeno of Elea, Pythagoras of Samos, the Eliastics Melissus, the Pluralists Anaxagoras of Clazomenae and Empedocles of Acragas, the Atomists Leucippus and Democritus of Abdera and the Sophists Diogenes of Apollonia. Aristotle refers to them as Investigators of Nature because of their interest on questions of physics (as the material principle).
- Presocratic interests extended to religious and ethical thought, the nature of understanding, mathematics, meteorology, the nature of explanation, and the roles of mechanism, matter, form, and structure in the world. Almost all the Presocratics seemed to have something to say about embryology, and fragments of Diogenes and Empedocles show a keen interest in the structures of the body; the overlap between ancient philosophy and ancient medicine is of growing interest to scholars of early Greek thought 
It was Pythagoras (ca. 582 - 504 BC) who first brought Philosophy into connection with practical life; he also gave Philosophy its name "the love of wisdom".
- According to a French historian of philosophy André Laks, the term "Presocratic" was probably coined by a German theologian Johann Augustus Eberhard who first used it in a section entitled "Presocratic Philosophy" (German: Vorsokratische Philosophie) in his 1788 manual of the universal history of philosophy. See: Laks, André. The concept of Presocratic philosophy : its origin, development, and significance. Transl. by Glenn W. Most. Princeton, NJ; Oxford : Princeton University Press, 2018. ISBN 9780691175454, p. . (online version retrieved 2019-08-24)
- Barnes, Jonathan. The Presocratic philosophers. 2nd rev. ed. London; New York, NY : Routledge, 1982. ISBN 0-203-00737-9, p. 3.
- Curd, Patricia. Presocratic Philosophy [online]. In Zalta, Edward N. (Ed.). Stanford Encyclopedia of Philosophy. Summer 2019 ed., 2016-04-04 (retrieved 2019-08-23)
- Barnes, Jonathan. The Presocratic philosophers. 2nd rev. ed. London; New York, NY : Routledge, 1982. ISBN 0-203-00737-9, p. .
- Presocratic Philosophy