It is called scholia (from the Latin scholium and this of the Greek σχόλιον, ‘comment’) to notes or brief comments grammatical , critical or explanatory, whether original or extracts from existing comments, which are inserted in the margins of the manuscript of an ancient author as a succinct gloss .
These notes were altered by successive copyists and owners of the manuscript and in some cases expanded to such an extent that there was no more room for them and it was necessary to transfer them to a separate book. At first they were taken from a single comment, and later from several. This is indicated by the repetition of the motto or by the use of phrases such as “or so”, “or on the contrary”, “according to some”, and so on; to present different explanations. Didymus of Alexandria is considered the first scholar dedicated to compiling scholia, a practice that continued until the Template: CENTURY or Template: CENTURY .
The word scholium was first used by Cicero ( Ad Atticum xiv.7). Most of the preserved Greek scholia are anonymous, with the prominent exceptions of Eustatius of Thessalonica’s comments on Homer and John Tzetzes on Lycophron . Often trivial, scholia contain much information not found elsewhere, and are of considerable value in correcting and interpreting the text. The most important are the facts about Homer (especially the Venetian scholia on the Iliad , discovered by Villoisonin 1781 in the library of San Marcos in Venice ), Hesiod , Pindar , Sophocles , Aristophanes and Apollonius Rodio , and, in Latin, those of Servius on Virgil , of Acro and Porfirio on Horace and those of Donatus on Terence .