Anastasius Sinaita a monk of Matthew Sinai, born, it is supposed, about 600, though the date is undecided. He is said to have traveled much in Egypt and Syria, defending the faith against the Acephalists, Severians, and Theodosians. In his "Odegos," or "Guide to the Right Path," he speaks of John who was the Theodosian patriarch of Alexandria from 677 to 686; he was consequently alive about that period, but when he died is not known. He is honored as a saint in the Greek Church. His principal work, the Odegos just mentioned, has been attributed by some writers to the patriarch Anastasius, who died in 598; but the fact just mentioned, viz., that John of Alexandria, who was patriarch from 677 to 686, is spoken of in it, will prove the impossibility of this. This work was published by Gretser, at Ingolstadt, in 1606. Some of the MSS. do not, however, contain the Exposition of the Faith, which is contained in Gretser's edition at the beginning, and differ in many other particulars. The complete works of Anastasius Sinaita have been published by Migne, in Patrologia Graect, tom. 89 (Paris, 1860).