Influential monastic author. Originating from [
Beth Qaṭraye
](https://gedsh.bethmardutho.org/Beth-Qatraye),
he was made bp. of [
Nineveh
](https://gedsh.bethmardutho.org/Nineveh) ([
Mosul
](https://gedsh.bethmardutho.org/Mosul)) by
Cath. Gewargis (661–81), perhaps ca. 676/80. After a short while, however,
he left (‘for reasons which only God knows’, as one of the two short
biographical accounts puts it) and became a hermit, attached to the
Monastery of Rabban Shabur, in the region of Shuster. His writings on
monastic spirituality come down in several ‘Parts’, three of which are now
known. The First Part, with 82 chapters, evidently circulated widely, and
much of it was translated into Greek at the Chalcedonian Monastery of Mar
Saba (St. Sabbas), near [
Jerusalem
](https://gedsh.bethmardutho.org/Jerusalem), in the
late 8th or early 9th cent. From Greek, his works were subsequently
translated into many other languages, in particular into Slavonic (whence
they were included in the Russian edition of the ‘Philokalia’). This Greek
translation also included (under Isḥaq’s name) three short works by [
Yoḥannan of Dalyatha
](https://gedsh.bethmardutho.org/Yohannan-of-Dalyatha), and an abbreviated form of [
Philoxenos
](https://gedsh.bethmardutho.org/Philoxenos-of-Mabbug)’s ‘Letter to Patricius’. The current printed editions
of the Greek translation go back to that by N. Theotokis (1770), and have a
different chapter numbering from that of the Syriac (a much-needed new
edition of the Greek text is in preparation by M. Pirard). A Second Part,
consisting of 41 chapters, is preserved complete in a single early ms. The
long third chapter of this Part consists of four ‘Centuries’ of short
sayings on spiritual knowledge (modelled on [
Evagrius
](https://gedsh.bethmardutho.org/Evagrius-of-Pontus)’s ‘Kephalaia Gnostica’). A Third Part has also recently come
to light, in a ms. in Tehran copied ca. 1900; this contains 17 chapters, two
of which are duplicates with the First Part, and one with the Second Part.
Though the Second and Third Parts were not translated into Greek, some
chapters from them have been identified in Arabic, and they were both
evidently known in Syriac monastic circles outside the Ch. of E., as well.
The ‘Book of Grace’, probably by [
Shemʿon
d-Ṭaybutheh
](https://gedsh.bethmardutho.org/Shemon-d-Taybutheh), has sometimes been wrongly attributed to Isḥaq.
Isḥaq’s monastic spirituality draws on many sources, both Syriac and Greek
(in Syriac translation); two authors would appear to have been particularly
appreciated by Isḥaq, [
Yoḥannan
Iḥidaya
](https://gedsh.bethmardutho.org/Yohannan-Ihidaya) and Evagrius. His teaching lays great emphasis on the
immensity of divine love and on the need for humanity to respond to this
with wonder and humility.