PLACIDO, saint. — Disciple of St. Benedict. His sole biographical source is the Dialogues of St. Gregory the Great (II, 3–7: PL 66, 140–46; critical edition by U. Moricca, Rome 1924, pp. 85–90), from which we learn that, at the age of seven, P. was offered to St. Benedict at Subiaco by his father Tertullus, a Roman patrician; having fallen into the Neronian Lake, where he had gone to draw water, he was miraculously brought ashore by St. Maurus (v.).
His cult underwent an evolution, which has been elucidated by U. Berlière (v. BIBLICA). The oldest documents commemorate him on 5 October as a “confessor.” In the second half of the 11th century, the opinion arose at Montecassino that the homonymous Sicilian martyr (v. voce sg), commemorated on that same day in the Hieronymian Martyrology, might be the disciple of St. Benedict; the hypothesis was embellished with fictional details by the librarian and archivist Pietro Diacono (d. ca. 1159) in the Vita (or Acta) in Placidi et fratrum eius Eutychii, Victorini ac Flaviae sororis etc., which he attributed to Gordianus, a presumed companion of the Saint who had escaped the pirates’ massacre at Messina (text in Mabilon, Acta SS. Ord. Benedict., I, Paris 1668, pp. 45–79; and in Acta SS. Octobris, III, Antwerp 1770, pp. 114–38). Therefore P.’s mission to Sicily to found monasteries there (like that of St. Maurus in Gaul) and his martyrdom belong to legend, although in the 16th century (v. voce sg) they entered the Breviary and the Roman Martyrology (5 October).