GUIDO, monk of MONTECASSINO. — He flourished under Abbot Gerard (1111–23) and was the teacher of Peter the Deacon (De viris illustribus Casinensis coenobii: PL 173, 1010), who describes him as «a man most distinguished in human learning, of proven piety and life» (ibid., 1044–45). From «certain venerable brethren» he received the task of putting into writing the vision that Alberic (q.v.), a monk of Montecassino—whom Guido may have instructed (A. Mirra, p. 35)—had experienced at the age of ten, and whose fame had spread widely.
Yet Guido’s work did not please, for «quamplus descripsit, quamplura dimisit» [he described more than he omitted], so much so that Alberic himself rewrote it, retaining only Guido’s prologue (ed. F. Cancellieri [q.V. BIBLICA.], pp. 144–45; A. Mirra [q.V. BIBLICA.], p. 86). According to Peter the Deacon (loc. cit.), Guido also composed a history of the emperor Henry (IV or V?), as well as some verses on the fortune of the same Vision, all now lost.