Aetius ( ) was a 1st or 2nd century doxographer and Eclectic philosopher.

None of Aetius' works survive today, but he solves a mystery about two major compilations of philosophical quotes. There are two extant books named Placita Philosophorum ( , "Opinions of the Philosophers") and Eclogae Physicae ( , "Physical and Moral Extracts"). The first of these is Pseudo-Plutarch and the second is by Stobaeus. They are clearly both abridgements of a larger work. Hermann Diels, in his great Doxographi Graeci, discovered that the 5th-century theologician Theodoret had full versions of the quotes which were shortened in the abridgements. This means that Theodoret had managed to procure the original book which Pseudo-Plutarch and Stobeaus had shortened. He calls this book "Aetiou t n peri areskont n sunag g n," and therefore we ascribe the original Placita to Aetius.

Diels claimed that Aetius himself was merely abridging a work which Diels called the Vetusta Placita (because he wrote his paper in Latin; literally, "Older Tenets"). Unlike Aetius, whose existence is attested by Theodoret, the Vetusta Placita is Diels' invention and is generally disregarded by modern classicists, e.g., the 1999 Cambridge History of Hellenistic Philosophy.

Quotes which are ascribed to Aetius in scholarly essays were actually discovered in either the abridgements of Pseudo-Plutarch or Stobaeus, or Theodoret's full quotes in rare cases, or finally one of several ancient authors who provided corrections to misquotes in one of these works.

External links

• John Burnet's Early Greek Philosophy: Section B: Note on the Sources
• Complete text of the Placita: Greek & French, English and French.

Bibliography

• Algra, Keimpe. The Cambridge History of Hellenistic Philosophy. Cambridge: Cambridge University Press, 1999.
• Mansfeld, Jaap, & Runia, David T. A tiana: The Method and Intellectual Context of a Doxographer, I: The Sources (Leiden: E. J. Brill, 1997) (Philosophia Antiqua, 73); Idem, A tiana: The Method and Intellectual Context of a Doxographer, II/1-2; The compendium (Leiden: E. J. Brill, 2009) (Philosophia Antiqua, 114); Idem, A tiana: The Method and Intellectual Context of a Doxographer. Vol. 3, Studies in the Doxographical Traditions of Ancient Philosophy (Leiden/Boston: Brill, 2009) (Philosophia antiqua, 118).

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