Dates   The only date regarding Thales' life that we know for certain, is the year that he predicted a solar eclipse, 585 B.C. The historian Apollodorus suggests that Thales was born in 625 B.C., but this claim should be accepted with some caution. Apollodorus tended to calculate birth dates on the assumption that a man was forty years old at the time of his greatest achievement.

Place of residence   Thales lived in the city of Miletus in Ionia in Northern Greece.

Philosophical school   Thales was the first of the Milesian philosophers, so called because they all resided in the city of Miletus. The Milesians, like Thales, were preoccupied with natural philosophy and with giving an account of the origins of the universe.

Philosophical interests   Thales' interests were broad ranging (for instance, he was famed as a military engineer), with his philosophical interests covering everything from natural philosophy, metaphysics, mathematics, and astronomy.

Available evidence for his thought   We have no direct quotations (fragments) from any work of Thales. In fact, it is not even clear that he wrote down any of his theories. Our only information regarding his philosophy comes from five separate reports (testimonia) in Aristotle, all of which seem to themselves come only from second-hand reports, not from any first-hand familiarity with Thales' work.

Dates   Anaximander was born in roughly 600 BC and lived until roughly 550.

Place of residence   Like Thales, Anaximander lived in Miletus, in Ionia, Greece.

Philosophical school   Anaximander was the second of the three Milesians.

Philosophical pedigree   Anaximander was almost certainly a student of Thales, and the teacher of Anaximines

Primary philosophical interests   Like his teacher, Thales, Anaximander's philosophical interests seem to have ranged over the subjects of natural philosophy, metaphysics, astronomy, and mathematics.

Available evidence for his thought   As with Thales, there are no direct quotations available from Anaximander's work, though we do know that he wrote books. The testimonia we have in the case of Anaximander are more numerous in number, however, than in Thales' case, and they also derive from a wider array of sources, including Aetius, Simplicius, and Pseudo-Plutarch in addition to Aristotle.

Dates   There are no known dates concerning Anaximines, though we do know that he was slightly younger than Anaximander.

Place of residence   Anaximines was also from Miletus, in Ionia Greece

Philosophical school   Anaximines was the last of the Milesians

Philosophical pedigree   Anaximines was probably a student of Anaxagoras.

Primary Philosophical Interests   As far as we know, Anaximines only concerned himself with natural philosophy and metaphysics.

Available evidence for his thought   With Anaximines, finally, we have some very short fragments in addition to testimonia.

Dates   Xenophanes was born in 570 B.C.

Place of residence   Xenophanes lived in Colophon, Greece, not far from Miletus.

Philosophical school   Xenophanes was not associated with any known philosophical school.

Philosophical pedigree   There is speculation that Xenophanes was the teacher of Parmenides at one time.

Philosophical Interests   Xenophanes did seem to engage in some natural philosophy and metaphysics, but his primary contributions are in the fields of theology and epistemology

Available evidence for his thought   We have quite a large number of very short fragments from the works of Xenophanes.

Dates   Heraclitus was born in 540 B.C.

Place of residence   Heraclitus lived in Ephesus, near Colophon.

Philosophical school   Like Xenophanes, Heraclitus is not associated with any known philosophical school.

Philosophical pedigree   As far as we know Heraclitus was neither the student nor the teacher of any other of the Presocratic philosophers. He did, however, forge his ties to history by rudely insulting all previous thinkers.

Philosophical interests   Heraclitus's thought has important implications in the fields of epistemology, natural philosophy, and metaphysics.

Available evidence for his thought   The evidence explodes at this stage. We have 115 reliable, but short, fragments for Heraclitus's thought.

Dates   Parmenides was born in 515 B.C. He published his revoltionary philosophical poem, On Nature, sometime between 470 and 460 B.C.

Place of residence   Parmenides was born in Elea, in southern Italy

Philosophical school   Parmenides was the founder of the Eleatic school, a movement intent on proving that reality is unchanging, eternal, and admits of no plurality.

Philosophical pedigree   Parmenides may have been the student of Xenophanes. Parmenides' most famous student, in turn, was Zeno, whose brilliant paradoxes baffled the Eleatic's opponents and continue to baffle modern thinkers.

Philosophical interests   Parmenides' thought had radical implications in the fields of epistemology and metaphysics.

Available evidence for his thought   We have some significant (both in content and in length) pieces of his poem On Nature. These pieces were preserved in various sources, such as the writings of Sextus Empiricus, Proclus, Simplicius, Plato, Plutarch, Galen, and Clement.

Dates   Empedocles was born 492 B.C. and died sometime around 424 B.C.

Place of residence   Empedocles lived in Acragas, Sicily

Philosophical school   Empedocles was the first of the pluralists, a school intent on maintaining, in the face of the Eleatic challenges, that the world exists roughly in the form in which we perceive it.

Philosophical pedigree   Empedocles was clearly heavily influenced by Parmenides, though whether he ever studied with members of the Eleatic school is unclear.

Primary philosophical interests   Empedocles was primarily interested in natural philosophy, metaphysics, and medicine. Like all post-Parmenidean thinkers, he also had an interest in epistemology.

Available evidence for his thought   Large pieces of his important philosophical poem have been preserved.

Dates   Anaxagoras was born in 500 B.C. In either 450 or 430 B.C., he was tried by Atheinian state for the crime of impiety and subsequently exiled to northern Ionia where he died soon thereafter.

Place of residence   Anaxagoras was born in Clazomenae in Ionia, but he spent most of life in Athens, before being exiled back to Ionia.

Philosophical school   Anaxagoras was a pluralist.

Philosophical pedigree   Like Empedocles, Anaxagoas was strongly influenced by Parmenides, but there is no evidence that he studied with him.

Primary philosophical interests   Anaxagoras's theories made important contributions in the fields of natural philosophy and metaphysics.

Available evidence for his thought   For Anaxagoras, we have a few large fragments and a few telling testimonia.

Dates   Leucippus' dates are unknown.

Place of residence   Leucippus's birthplace has been given variously as Abdera, Miletus, and Elea.

Philosophical school   Leucippus was the founder of atomism, which can be viewed as a sub-movement within the larger movement of pluralism.

Philosophical pedigree   Leucippus was probably a student of Zeno and was undoubtedly the teacher of Democritus.

Philosophical interests   Leucippus' brand of atomism could not have failed to touch upon natural philosophy and metaphysics. Whether he had other interests besides is unknown, since none of his work remains.

Available evidence for his thought   There is single fragment, one sentence long, testifying to Leucippus' thought.

Dates   Democritus was born in 460 B.C. and died in 375 B.C.

Place of residence   Democritus was born in Abdera, Thrace in Northern Greece, but he traveled extensively throughout the ancient world.

Philosophical school   Democritus was the philosopher responsible for bringing atomism to public attention.

Philosophical pedigree   Democritus was the student of Leucippus.

Primary philosophical interests   Demorcitus believed that atomism could be usefully applied to all fields of inquiry. He wrote treatises covering natural philosophy, epistemology, metaphysics, ethics, politics, and mathematics, among other subjects.

Available evidence for his thought   Most of our evidence regarding the thought of Democritus comes from in depth testimonia, but there are also some shorter fragments in existence.