A man unique in the extent of his knowledge and chief among the doctors of the church, Jacob had a brilliant mind, critical temperament, sharp wit and sound judgment. He was a grammarian, a man of letters, a poet, a translator, an historian, a commentator, a legislator and a philosopher-theologian. He was prominent in each one of the sciences which he had acquired, showing great capability and skill in writing. In the earlier periods he had no equal, and among the scholars of later periods, his extensive knowledge was rivaled only by that of Bar Hebraeus. By his vocalization of the Books of the two Testaments, he preserved the Holy Bible from distortion and misspelling; his revision of translations of some works of the doctors of the church, show that he was highly proficient in philology. His philosophical and theological books prove that he was the most distinguished and the finest scholar of his time; his interesting letters contain knowledge and wisdom; his legal opinions and juristic ideas prove that he had a sound mind, a guiltless heart and perceptive individual judgment. Consequently he shows himself judge of creative as well as traditional knowledge within both of which lies the final decision. This is due to the fact that he used opinions--of the Christian authorities and blended them with his own intelligent opinions. Finally his ritual books leave no doubt that he is the greatest doctor of the church and the bearer of the banner of its glory. His books are the end beyond which there is no further quest for a researcher. It is no surprise that he is considered unequaled in all the East and the most prominent of all the Syrian scholars in the ancient world as well as in the Middle Ages.

Mor Jacob was born at the village of Ayndaba in the district of Gumyah, in the province of Antioch, most probably about 633/40. The name of his father is thought to be Isaac. Under Father Kyriakos, the predutes (visiting cleric) of his province he studied the principles of the sciences, the books of the two Testaments and the books of the doctors of the church. Then he went to the Monastery of Qinneshrin where he became a monk and studied the literature of the Greek language under Severus Sabukht. Together with his companion Athanasius of Balad, who was older than he, he completed his studies and became well versed in philology, philosophy and theology. Also he became well-trained in the ascetic and virtuous life. Then he journeyed to Alexandria to penetrate more deeply into the minutiae and incomprehensibilities of philosophy. He returned to Damascus (al-Sham), became a monastic at Edessa and studied Hebrew. At Edessa, he achieved wide fame. He was sought by scholars and lovers of learning, who corresponded with him about problems which he competently answered.

In 672 he was ordained a deacon and then a priest. In 684, he was chosen and was ordained by his friend Patriarch Athanasius II, a metropolitan of Edessa, from which he received his generic name. He remained in Edessa four years, during which he became very strict with the monks and clergy concerning the observation of laws that had been neglected. He expelled those who disobeyed him. In the meantime, the patriarch Julian II and the bishops advised him to temporize and treat the clergy as tolerantly as conditions would permit. This suggestion made him more furious and, thereupon, he openly burned a copy of the neglected canonical rules, resigned his see and left the diocese, taking with him his pupils Daniel and Constantine to the Monastery of St. Jacob in Kesum (near Samosata). while the more lenient Habib succeeded him as metropolitan of Edessa.

Shortly afterwards he accepted the invitation of the monks of Eusebona (in the Diocese of Antioch) to reside at their convent, and there he commented for eleven years on the Sacred Scriptures in the Greek text, doing his utmost to promote the study of the Greek tongue. After a short period, he was appointed a teacher of the Greek language at the same Monastery of Eusebuna, where he revitalizing the study of this language. He also commented on the Holy Scriptures according to the Greek version. And when some of the monks who hated the Greeks showed disagreement, he left for the Monastery of Talada accompanied by seven pupils. He remained at Talada about nine years, devoting his time to the revision of the translation of the Old Testament. The Book of Kings which he had translated in 705 is preserved at the library of Paris.

At the end of 707, upon Mor Habib's death the congregation of Edessa requested Mor Jacob to return to them, recognizing his excellence. he took possession again of the Episcopal See of Edessa at the end of January 708, resided in that city for four months, and then went to Tell-Adda to fetch his library and his pupils, and he died there on the fifth of June, which is also the day of his commemoration. He was nicknamed "the man who preferred toil" or "the militant" as well as "the translator of books."

St. Jacob was zealous and saintly high-minded. He was also hot-tempered, of great determination and no leniency; thus, he was unable to administer the affairs of his congregation amicably. In this regard he shares similar characteristics with the very learned Gregory Nazianzen. Nevertheless, his resignation provided him the opportunity to spend the ripest years of his life in the service of knowledge. Therefore, he benefited the Church of God in ways he would have been unable to had he remained in his diocese.

For his time, his erudition was extensive. He was not only familiar with Greek and with older Syriac writers, but he also had some knowledge of Hebrew, and willingly availed himself of the aid of Jewish scholars, whose views he often records. His writings, which are not all extant, were very varied and numerous. Among them may be noticed first, his important revision of the Old Testament. This work was essentially Massoretic. St. Jacob divided the Sacred Books into chapters, prefixing to each chapter a summary of its contents. He supplied the text with numerous marginal notes, of which one part gives readings from the Greek and the Syrian versions at his disposal, and the other part indicates the exact pronunciation of the words of the text. Some of the notes contain extracts from Severus of Antioch; while, at times, glosses are inserted in the text itself. Unfortunately, only portions of this revision have come down to us. These are: practically the whole Pentateuch and the Book of Daniel, preserved in the Bibliothèque Nationale at Paris (Syric. nos. 26, 27); the two Books of Samuel with the beginning of Kings, and the prophecy of Isaiah, found in the British Museum (Add. 14429, 14441). The other principal writings of St. Jacob of Edessa on Biblical topics are: (1) his unfinished "Hexameron", or work on the six days of creation, which is divided into seven treatises, and which opens with a dialogue between the author and Constantine, one of his disciples. Jacob's "Hexaemeron" is preserved in two MSS., one of which is found in Leyden, and the other in Lyons; (2) commendaries and scholia on the Sacred Writings of both Testments, which are cited by later authors such as Mor Dionysius bar-Salibi, Mor Bar-Hebraeus, and Mor Severus. Some of his scholia have been published in the Roman edition of the works of St. Ephraim, and, at different times, by Phillips, Wright, Schröter, and Nestle; (3) letters treating of questions relative to Holy Writ, and mostly yet unpublished. As a liturgical author, Jacob of Edessa drew up an anaphora, or liturgy, revised the Liturgy of St. James, wrote the celebrated "Book of Treasures", composed orders of baptism, of the blessing of water on the eve of the Epiphany, and of the celebration of matrimony, to which may be added his translation of Severus's order of Baptism, etc. He is also the author of numerous canons; of important homilies, a few of which survive in MS; of a valuable "Chronicle" which he composed in 692, and of which a few leaves only are extant; of an "Enchiridion", or tract on technical philosophical terms; of a translation of the "Homiliae Cathedrales", written in Greek by Severus of Antioch; and of the "Octoechus" by the same author; of a biography of Jacob of Sarugh, of a translation from the Greek of the apocryphal "History of the Rechabites", of a Syriac grammer, a few fragments of which are extant in Oxford and London, and in which he advocated and illustrated a novel system of indicating the vocalic element not found in the Syrian alphabet; and, finally, of an extensive correspondence with a large number of persons throughout Syria.

For more information on his writing please refer to: History of Syriac Literature and Sciences, Patriarch Ignatius Ephrem I Barsoum, Presseggiata Press, p 110.