Heidegger's Bible Handbook: New Testament in General: Chapters

5. Whence had κεφάλαια/chapters their name? Stephanus call them Tmemata/sections.

The other division is according to κεφάλαια/chapters, or little-headings, which, although sometimes they are equivalent with those sections, as it is to be seen in Œcumenius[1] and others, yet they are more frequently parts of sections, smaller than the sections themselves. Their metaphor was sought, not from a manner of counting, but from the very order of the text of the books, and the very variety of the arguments: so that they are called chapters, because from the diversity of the argument, matters, and order they constitute a new chapter and a new part, and are distinguished by a certain space and greater letters. In the same sense the Rabbis called chapters פרקים/Pirkim, breaks/fractions, as it were, because they interrupt the series of the text, and break it into more parts. But Robertus Stephanus prefers to call them Tmemata/sections, rather than chapters.

[1] Œcumenius was thought to have been a late-tenth century bishop of Trikkala in Thessaly, but the authorship of the commentaries traditionally ascribed to him is confused. The commentaries on Acts and the Catholic Epistles are the same as those of Theophylact of Bulgaria (eleventh century); the commentary on the Pauline Epistles is older, copied in part from the work of Andrew of Cæsarea (563-637); the commentary on the Apocalypse appears to have been composed around the turn of the seventh century. Arethas of Cæsarea (ninth century) was a Greek Orthodox bishop and scholar. He compiled scholia on the Apocalypse, the oldest extant. Arethas’ comments on the Apocalypse were appended to the work of Œcumenius in this 1532 edition.