Greek Philosophers
Anaximenes (Greek: Άναξιμένης) of Miletus (585 BCE - 528 BCE): held that the air, with its variety of contents, its universal presence, its vague associations in popular fancy with the phenomena of life and growth, is the source of all that exists.
Heraclitus (Greek: Ἡράκλειτος) of Ephesus (ca. 535 - 475 BCE) disagreed with Thales, Anaximander, and Pythagoras about the nature of the ultimate substance and claimed instead that everything is derived from the Greek classical element fire, rather than from air, water, or earth.
Empedocles (ca. 490 BCE – ca. 430 BCE) was a citizen of Agrigentum, a Greek colony in Sicily. Empedocles' philosophy is best known for being the origin of the cosmogenic theory of the four classical elements.
Anaxagoras of Clazomenae (ca. 500-428 BCE) regarded material substance as an infinite multitude of imperishable primary elements, referring all generation and disappearance to mixture and separation respectively.
Archelaus was a Greek philosopher of the 5th century BCE, born probably in Athens. He was a pupil of Anaxagoras, and is said by Ion of Chios (Diogenes Laërtius, ii. 23) to have been the teacher of Socrates.
Hippo (ca. 425 BCE) was native of Magna Graecia (Italy). Very little is known about him. He held that water was the principle of all things.
Diogenes (ca. 425 BCE) was a native of Apollonia, either the one in Crete or in Thrace. Like Anaximenes, he believed air to be the one source of all being.
Socrates (Greek: Σωκράτης,) (469 BC–399 BC) was a Classical Greek philosopher. Credited as one of the founders of Western philosophy, he is an enigmatic figure known only through the classical accounts of his students. Plato's dialogues are the most comprehensive accounts of Socrates to survive from antiquity.