Marcus Valerius Probus (MAHR-kuhs vuh-LIHR-ee-uhs PROH-buhs) spent his life studying old Latin authors and texts that were not popular in Rome, where he spent at least some of his adult life. Valerius Probus did not establish an official school to study grammar, paleography, and Latin literature, but his reputation as a careful textual scholar was so well known that he acquired a small group of scholars as his students. He was concerned primarily with preserving the accuracy of older Latin texts, particularly the works of Vergil, Horace, and Terence. Many copies of works by these authors had been made, and numerous scribal errors and notations, inaccurate emendations, and misreadings had crept into published versions of well-known texts. Valerius Probus produced more accurate versions of older Latin texts and included various marginal notations to indicate how a disputed phrase was to be read. He worked from the oldest and therefore theoretically most accurate manuscript of a text. He claimed to have produced a copy of the works of Vergil based on an ancient manuscript written by Vergil himself.