Greek monastic writer of uncertain identity; author of the Asceticon ( CPG 5555). Two possible Isaiah’s are known, Isaiah of Scetis (early 5th cent.) and Isaiah of Gaza (d. 491). The suggestion (by G. Krüger, in Die sogenannte Kirchengeschichte des Zacharias Rhetor, ed. K. Ahrens and G. Krüger [1899], 385–6), that these two were really a single person, was widely accepted until Draguet’s edition of the Syriac translation. Draguet firmly distinguished the two and saw the Asceticon as the work of Isaiah of Scetis. Subsequent scholarship has hesitated in accepting this, but a possible solution is that the earliest form of the work (now discernable through Draguet’s edition) goes back to Isaiah of Scetis, while the later form represents the editorial work of Isaiah of Gaza, a friend of Peter the Iberian and of Severus (this Isaiah’s Life was written by Zacharias ; ed. with LT, by E. W. Brooks [CSCO 7–8; 1907]). The identity, or otherwise, of the two Isaiah’s is reflected in recent dictionary articles: some treat them together (thus Regnault), while others deal with them separately (thus Aubert). The Syriac translation of the Asceticon survives in many mss. and (for several of the Discourses) in two different forms. The work was clearly widely read in Syriac monastic circles, both East and West. In the late 7th cent. Dadishoʿ composed an extensive commentary on it, and a further anonymous commentary is also preserved in an incomplete form.