The Latin word for “chain,” it was originally used to describe biblical commentaries, from about a.d. 400 onward, in which portions of Scripture were explained by means of chains of sentences or paragraphs derived from earlier commentaries, without any personal comment by the compiler. Later it was used of collections of writings by different authors, which related to one topic—e.g., a gospel. Thomas Aquinas made a famous collection of the gospels, the Catena Aurea.