746 LEO. emperor and the caliph Al-Maraoun ; and, falling into the hands of the Moslems, or treacherously- deserting to them, at the fall of Amoriura (a.d. 839), became known to the caliph, who was a liberal patron of science. The young man, though he excited the admiration of the caliph and his court, by his geometrical attainments, professed himself to be " not a master, but only a learner, and so highly extolled the knowledge of Leo, that he was forthwith despatched to Constantinople, with a letter to him, inviting him to leave that city and resort to Bagdad. Fearful of being suspected of a treasonable correspondence with the enemy, Leo showed the letter to the logothete Theoctistus, by whom the matter was reported to the emperor. Leo was thus made known to Theophilus. The emperor first appointed him public teacher or pro- fessor, assigning him the church of the Forty Martyrs as a school, and soon after ordered the patriarch Joannes, who appears hitherto to have neglected his learned kinsman, to ordain him arch- bishop of Thessalonica (Theoph. Continuat. iv. 27 ; comp. Symeon Magister, De Tkeopldlo. c. 18 — 20; Georg. Monach. De TheopUlo. c. 22, 23 ; Cedrenus, Compendium, I.e.; Zonar.xvi,4). After three years, when Theophilus died (a. d. 342), and the govern- ment came into the hands of his widow Theodora, as the guardian of her son Michael, the iconoclastic party was overthrown, and Leo and Joannes were deposed from their sees : but Leo, whose worth appears to have secured respect, escaped the suffer- ings which fell to his kinsman's lot (Theoph. Cont. iv. 9, 26 ; Sym. Mag. De Theoph. c. 20, De Mi- chaele, c 1) ; and when the Caesar Bardas, anxious for the revival of learning, established the Mathema- tical school at the palace of Magnaura, in Constan- tinople, Leo was placed at its head, with one, if not more of his former pupils for his fellow-teachers. (Theoph. Contin. iv. 26 ; Cedrenus and Zo- naras, II. cc.) Leo was faithful to the interests of Bardas, whom he warned of the insidious designs of Basilius the Macedonian, afterwards emperor (Sym. Mag. De Michaele et T/ieodora, c. 40 ; Georg. Monach. De Mich, et T/ieodora, c. 25, 26). An anecdote recorded both by Symeon {De Basilio Maced. c. 5) and George {De Basil. Maced. c. 4), shews that Leo was living in A. D. 869 : how much later is not known. Symeon {De Mich, et Theodora, c. 46) has de- scribed a remarkable method of telegraphic com- munication, invented by Leo, and practised in the reigns of Theophilus and his son Michael. Fires kindled at certain hours of the day conveyed intel- ligence of hostile incursions, battles, conflagrations, and the other incidents of war, from the confines of Syria to Constantinople ; the hour of kindling in- dicating the nature of the incident, according to an arranged plan, marked on the dial plate of a clock kept in the castle of Lulus, near Tarsus, and of a corresponding one in the palace at Constantinople. Leo AUatius, in his Excerpta Varia Graecor. Sophistarum, has given (p. 398) Aeovros rod *i/o- ff6(l>ov KapKiVot, Versus Carcini Leonis Philosophic i.e. verses which may be read either backward or forward. They are probably the same which are in some MSS. or catalogues ascribed to Leo Gram- maticus [see above, No. 15], but may be more pro- bably ascribed to our Leo, among whose early studies poetry is mentioned. Several astrological collectanea extant in MS. in different European libraries, contain portions by Leo Philosophus, by LEO. which name the subject of the present article, who appears to have practised astrology (Theoph. Contin. iv. 28, v. 14), is probably meant (Fabricius, Bibl. Grace, vol. iv. p. 148, Graec. De Mard Biblioth. p. 153; Catalog. Codd. MStorum Bill. Reyiae, Paris, fol. 1740, vol. ii. pp. 499, 500): but the MtfloSos irpoyvcacTTLK-^, Methodus Frognostica or instructions for divining by the Gospel or the Psalter, by Leo Sapiens, in the Medicean library at Florence (Ban- dini. Catalog. Codd. Laur. Medic, vol. iii. p, 339), is perhaps by another Leo. Comb^fis was disposed to claim for Leo of Thessalonica the authorship of the celebrated Xprja/xol, Oracula, which are commonly ascribed to the emperor Leo VI. Sapiens, or the wise, and have been repeatedly published. But Leo of Thessalonica is generally designated in the Byzan- tine writers the philosopher {^LX6(TO(pos), not the wise {aocpos), and if the published Oracula are a part of the series mentioned by Zonaras (xv. 21), they must be older than either the emperor or Leo of Thessalonica. (Fabric. BiU. Graec. vol. iv. pp. 148, 158, vol. vii. p. 697, vol. xi. p. 665 ; Allatius, De Psellis, c. 3 — 6 ; Labbe, De B>/zant. Hidor. Scrip- torib. nporpeirriKou, pars secunda, p. 45.) [J. CM.] LEO, Latin ecclesiastics. 1, The first of that name who occupied the papal throne, is usually styled the Great. He was a native of Rome, and must have been born towards the close of the fourth century, although the precise year is unknown. Nothing has been recorded con- cerning his parents, except that his father was called Quintianus, nor with regard to his early training ; but when we remark the erudition and polished accuracy displayed in his writings, and the early age at which he rose to offices of high trust, it becomes manifest that his great natural talents must have been cultivated with uncommon assiduity and skill. While yet an acolyte he was despatched, in A. D. 4 1 8, to Carthage, for the pur- pose of conveying to Aurelius and the other African bishops the sentiments of Zosimus concerning the Pelagian doctrines of Coelestius. [Coelestius] Under Coelestinus [Coelestinus] he discharged the duties of a deacon ; and the reputation even then (431) enjoyed by him is clearly indicated by the terms of the epistle prefixed to the seven books, De Incarnatione Ckristi, of Cassianus, who at his request had undertaken this work against the Nestorian heresy. Having obtained the full con- fidence of Sixtus IIL, to whom he rendered much good service, he attracted the notice of Valentinian IIL, and by the orders of the emperor undertook a mission to Gaul, in order to soothe the formidable dissensions of Aetius and Albinus. [Aetius.] While Leo was engaged in this delicate negotiation, which was conducted with singular prudence and perfect success, the chief pontiff died, and by the unanimous voice of the clergy and laity the absent deacon was chosen to fill the vacant seat, and on his return was solemnly installed, a. d. 440. From the earliest ages until this epoch no man who combined lofty ambition with commanding intellect and political dexterity had presided over the Roman see: and although its influence had gradually increased, and many popes had souglit to extend and confirm that influence, yet they had merely availed themselves of accidental circum- stances to augment their own personal authority, without acting upon any distinct and well devised scheme. But Leo, while he sedulously watched over the purity of his own peculiar flock, conccn-
