ARSACIO, saint. — Confessor, died c. 358 at Nicomedia. According to Sozomen (Hist. eccl., IV, 16), he was Persian by birth, confessed the faith under Licinius, and, after serving for some time in the imperial palace, withdrew to an eremitical life at Nicomedia, where he died a victim of the earthquake—foretold by him—that destroyed the city on 24 August 358. In the Middle Ages, the cult of s. A. was known in Naples, Milan, and Bavaria. Late legends made him a disciple and successor of s. Ambrogio, or a brother of s. Eustorgio II, archbishop of Milan. The Roman Martyrology commemorates him on 16 August.
BIBL.: Martyr. Romanum, p. 343; Acta SS. Augusti, III, Paris 1867, pp. 270–73; G. Ratzinger, Der hl. Arsatius von Illmünster, in Theol. prakt. Monatschrift, 2 (1892), p. 493 ff. Mario Scaduto