(Εὐστράτιος), a presbyter of the Greek church at Constantinople, is the author of a work on the Condition of the Human Soul after Death, which is still extant. Respecting his life and the time at which he lived, nothing is known, except what can be gathered from the work itself. It is directed against those who maintainted that the souls ceased to act and operate as soon as they quitted the human body. Photius (Bibl. Cod. 171) knew the work, and made some extracts from it, which is a proof that Eustratius must have lived before Photius. Further, as Eustratius repeatedly mentions the works of Dionysius Areiopagita he must have lived after the publication of those works, which appear to have been circulated about A. D. 500. It is therefore very probable that Eustratits lived at the time of Eutychius, patriarch of Constantinople, that is, about A. D. 560, as in fact Eustratius himself says in almost as many words. His work was first edited by L. Allatius in his de Occidentalium atque Orientalium perpetua in Dogmate Purgatorii consensione, Rom. 1655, 8vo., pp. 319-581. The style of Eustratius, as Photius remarks, is clear, though very different from classic Greek, and his arguments are generally sound. (Fabric. Bibl. Graec. vol. x. p. 725; Cave, Hist. Lit. vol. i. p. 416.) Some other persons of the name of Eustratius are enumerated by Fabricius. (Bibl. Graec. vol. iii. p. 264, note.)