The only writings that have survived from the Pyrrhonean skeptics, named after the followers of Pyrrho of Elis (367-275 B.C.E.), are those of Sextus Empiricus...A medical doctor and teacher, [he] was the last leader of the Pyrrhonean movement. His written works are copies of lectures consisting of arguments worked out by previous skeptics. His Against the Mathematicians and Against the Dogmatists contain detailed arguments against each area of knowledge: the liberal arts (grammar, rhetoric, geometry, arithmetic, astronomy, and music), and what then were three branches of philosophy - logic, physics, and ethics. Ironically, [the above mentioned works] are two of the most important sources of knowledge about the early history of astronomy, geometry, grammar, and the prevailing Stoic theology of the time.

bio by Daniel Kolak in Lovers of Wisdom
(Wadsworth, 1997)