Gelasius (13) of Cyzicus, in 2nd half of the 5th cent., author of a work on the history of the council of Nicaea, entitled by Photius The Acts of the First Council in Three Books. Our only knowledge of the author is derived from himself. Photius acknowledges his inability to determine who he was. We learn from Gelasius's own words that he was the son of a presbyter of Cyzicus, and, while still residing in his father's house, fell in with an old parchment volume which had belonged to Dalmatius, bp. of Cyzicus, containing a long account of the proceedings of the council of Nicaea. This document not supplying all the information he desired, Gelasius examined the works of other writers, from which he filled up the gaps. He mentions the work of an ancient writer named John, a presbyter otherwise unknown, the works of Eusebius of Caesarea and Rufinus (whom he calls a Roman presbyter), who were both eye-witnesses, and many others. From these and other sources Gelasius compiled his history of the Nicene council. It is sometimes taken for granted that it contains a complete collection of the synodal acts of the council. There is, however, no evidence of the existence of such a collection, or of any one having seen or used it. Athanasius had none such to refer to (cf. Athan. de Decret. Syn. Nic. 1. 2), and certainly we do not possess it in Gelasius (cf. Hefele, Hist. of Councils, Eng. trans. 263, 264). From the work itself we learn that it was composed in Bithynia. As an historical authority it is almost worthless. Its prolix disputations and lengthy orations are, as Cave has justly remarked, evidently the writer's own composition. Dupin's verdict is still more severe. "There is neither order in his narrative, nor exactness in his observations, nor elegance in his language, nor judgment m his selection of facts, nor good sense in his judgments." Instances of his untrustworthiness are seen in his statements that the council was summoned by pope Sylvester, and that Hosius of Cordova presided as his delegate; and he devotes many chapters (ii. 11â€“24) to disputations on the divinity of the Holy Spirit, which had not then come into controversy at all. The work is in vol. ii. of Labbe's collection (col. 103â€“286) and in those of Harduin and Mansi. Phot. Biblioth. Codd. 15, 88, 89; Fabric. Biblioth. Graec. v. 24, vi. 4; Cave, Hist. Lit. i. 454; Dupin, iv. 187; Le Quien, Or. Christ. iii. 568.