St. Isaac was born in the region of Qatar on the western shore of the Persian Gulf. When still quite young, he entered a monastery with his brother. His fame grew as a holy man and teacher. He was subsequently ordained bishop of Nineveh, the former capital of Assyria to the north, but requested to abdicate after only five months. He then went south to the wilderness of Mount Matout, a refuge for anchorites. There he lived in solitude for many years studying the Scripture, but eventually blindness and old age forced him to retire to the monastery of Rabban Shabur, where he reposed and was buried. His feast day is January 28.
Much has been made in some circles that St. Isaac was a member of the Church of Persia (known today at the Assyrian Church of the East), which has been associated with the Nestorian heresy. The first edition (1984) of the Orthodox English translation of St. Isaac's Ascetical Homilies contained an extensive Epilogue entitled "A Brief Historical and Theological Introduction to the Church of Persia to the End of the Seventh Century," written by Syriac scholar Dr. Dana R. Miller of Fordham University, which has been summarized thusly in the new (2011) more compact second edition: "Saint Isaac was and still is commonly called 'Nestorian Bishop of Nineveh' and the Church of Persia of his day, 'Nestorian'. The [first edition] Epilogue endeavored to demonstrate that the teachings of Nestorius did not inform the theology of the Church of Persia; that the writings of Theodore of Mopsuestia known to her were partial and imperfect translations, and that the controversy his writings caused in the Greek-speaking world were mostly unknown to the Church of Persia, cut off by linguistic differences and political boundaries; that in some cases it was extremism on the part of the Monophysites that led the Church of Persia to take a stance that might seem to lend itself to a Nestorian interpretation, such as the cautious avoidance of the term Theotokos to avoid Monophysite Theopaschism, though she professed the Virgin's Son to be perfect God and perfect man; that the fraternal relations with Byzantium remained open: no general and hardened opposition to the Fourth [Ecumenical] Council created a final division between the Church of Persia of Saint Isaac's day and the 'Chalcedonian' Church, as it did with the Monophysites, for whom the rejection of the Council of Chalcedon became a defining element of their identity. Its aim, in a word, was to show that the Church of Persia to which Saint Isaac belonged was neither heretical in theology nor schismatic in confession." (pages 74-75, "Ascetical Homilies of Saint Isaac the Syrian", Revised Second Edition, translated and published by Holy Transfiguration Monastery, Brookline, MA, 2011)
"Be persecuted, rather than be a persecutor. Be crucified, rather than be a crucifier. Be treated unjustly, rather than treat anyone unjustly. Be oppressed, rather than zealous. Lay hold of goodness, rather than justice."
"A small but always persistent discipline is a great force; for a soft drop falling persistently, hollows out hard rock."
"The Lord's Day is a mystery of the knowledge of the truth that is not received by flesh and blood, and it transcends speculations. In this age there is no eighth day, nor is there a true Sabbath. For he who said that `God rested on the seventh day,' signified the rest [of our nature] from the course of this life, since the grave is also of a bodily nature and belongs to this world. Six days are accomplished in the husbandry of life by means of keeping the commandments; the seventh is spent entirely in the grave; and the eighth is the departure from it." -- The Ascetical Homilies, I
"Why do you trouble yourself in a house that is not your own? Let the sight of a dead man be a teacher for you concerning your departure from hence."
"The knowledge of the Cross is concealed in the sufferings of the Cross."
"The man who follows Christ in solitary mourning is greater than he who praises Christ amid the congregation of men."
"Why do you increase your bonds? Take hold of your life before your light grows dark and you seek help and do not find it. This life has been given to you for repentance; do not waste it in vain pursuits."
- The Ascetical Homilies of Saint Isaac the Syrian, by Holy Transfiguration Monastery (1984). ISBN 978-0913026557.
- The Ascetical Homilies of Mar Isaac of Nineveh, by Paul Bedjan (2007). ISBN 978-1593333898. (Texts of the homilies are in Syriac.)
- The Ascetical Homilies of Saint Isaac the Syrian, Revised Second Edition, by Holy Transfiguration Monastery (2011). ISBN 978-0943405162
- Mystical Treatises by Isaac of Nineveh, by A. J. Wensinck (1923). Reprinted by Lulu.com
- Isaac of Nineveh (Isaac the Syrian) 'The Second Part', Chapters IV-XLI, by Sebastian Brock (1995). ISBN 9068317091
- Hilarion Alfeyev, The Spiritual World of Isaac the Syrian (2004). ISBN 978-0879077754.
- isaacthesyrian.com: A collection of resources on St. Isaac
- Pearls from Saint Isaac of Syria
- PEARLS of Saint Isaac from Syria compiled by Fr. Pius Sammut
- OCA - Lives of all saints commemorated on January 28 (including St. Isaac the Syrian the Bishop of Nineveh)
- St. Isaac of Nineveh