A critical or explanatory note or collection of notes on a sacred or literary work, accompanying the text or issued separately, usually written by a person or persons other than the author.Click here to see a 12th-century copy of a commentary on Cicero's "Scipio's Dream" written in the 5th century by Macrobius (Royal Library of Denmark). Commentaries are often devoted to major works that have been the subject of considerable interpretation, such as the Bhagavad-Gita, Bible, Qur'an, etc. (click here to see a 10th-century example). In medieval manuscripts, commentary was often written as a gloss alongside the text to which it referred (click here to see a 13th-century example, courtesy of the Metropolitan Museum of Art). Also refers to a historical narrative written largely from personal experience, for example, Seven Commentaries on the Gallic War by Julius Caesar. Synonymous in this sense with memoirs.
In a more general sense, a series of remarks or observations made by someone with authority to speak and be heard on the subject, for example, a journalist writing a column on a political or social issue.

Reitz Joan M. (2004)