Isaac De Beausobre, the Huguenot author of one of the best books ever written on Manichæism (Histoire critique de Manichée et du Mani cheïsme, Amsterdam, 1734, 1739), was the one to make the only sound suggestions on the sources used by Mani for the compilation of his Book of the Giants: the Book of Enoch, and the which Kenan, a great-grandson of Noah, discovered lying in a field (vol. i, 429, n. 6). The latter work has been indentified by Alfaric (Lex Écritures Manichéennes, ii, 32) with a book whose contents are briefly indicated in the Decretum Gelasianum, p. 54, II. 298–9 (ed. Dobschütz): Liber de Ogia nomine gigante qui post diluvium cum dracone ab hereticis pugnasse perhibetur apocryphys. Of the Book of Enoch, which was composed in the Hebrew language in the second century B.C., only an Ethiopic version, a few Greek fragments, and some excerpts made by the Byzantine chronographer Georgius Syncellus survive. Mani, who could hardly read the Hebrew, must have used an Aramaic edition based directly on the Hebrew text (see below, Šhmyz'd). He quotes mainly from the first part, which Georgius S. (p. 45, EI.-R.) called “the first book of Enoch on the Egrēgoroi”, but shows himself acquainted also with the subsequent chapters.