Demetrius ascended to the episcopate of Alexandria, Egypt in A.D. 179 A.D. or 189. "He was illiterate. He was a countryman, a rustic layman who could neither read nor write, he even had a wife, which ordinarily would disqualify him for high church office. But his predecessor had been told in a vision on his death bed, it is related [by Jerome], that the man chosen by heaven as the next bishop would appear the next day bringing a present of grapes. Precisely on schedule the unsuspecting Demetrius showed up carrying bunches of grapes from his farm and was taken almost by force, hastily ordained, and thrust against his will upon the 'throne of St. Mark'(A History of Christianity in Asia, Vol. l., Samuel Hugh Moffett, Orbis) as the twelfth Patriarch of Alexandria (Mark is considered by the Church Fathers as the one who preached the Gospel in Egypt). Surprisingly, Demetrius ruled the Egyptian church long and well for 42 years and built the catechetical school attached to his cathedral into a world-famous center of learning.
From the School of Alexandria and the ministry of this illiterate bishop, two good things came about.
1. There came out two great teachers of the way of Christ who so influenced the Christianity which would follow - Clement of Alexandria and Origen (whom he exiled for an unknown reason).
2. Demetrius chose the headmaster of his school even before Clement and Origen came forth, who was totally the opposite of himself, to go on a special mission. His name was Pantaenus. Pantaenus was a Jew who had come to believe in Christ and was an intellectual, originally from Sicily, the "Sicilian bee"- named for his diligence in the study of Greek Philosophy. Demetrius chose Pantaenus to go to India as a "herald of the Gospel of Christ" (Eusebius) on invite of Hindu philosophers, who wanted to know more about Christ. Arriving in India, Pantaenus found a small but thriving Christian community, and he reported back that he even found the Gospel of Matthew written in Hebrew, reportedly brought there by Bartholemew (bar Tolmai, a disciple of the Lord), after Thomas, one of the 12 Apostles, had gotten there. Scholars say that that "Hebrew" Gospel was really in Aramaic, as "Hebrew" was sometimes a cover-term for Aramaic, and because the community of believers immediately after was Aramaic speaking, centering in the seven Jewish cities known to be in southern India from the 1st century (Southern India - Kerala and environs would become the center for the Aramaic Church in India). Today, most of the descendants of this community of Jews, part of the Bene Israel, are living in Israel.