Isaac is remembered for his spiritual homilies on the inner life, which have a human breadth that transcends the Nestorian Christianity of the Church to which he belonged. They survive in Syriac manuscripts and in Greek and Arabic translations. From Greek they were translated into Russian.
Isaac of Nineveh
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Isaac consciously avoided writing on topics that were disputed or discussed in the contemporary theological debates. This gives Isaac a certain ecumenical potential, and is probably the reason that he has come to be venerated and appreciated among many different Christian traditions.
Isaac stands in the tradition of the eastern mystical saints and placed a considerable emphasis on the work of the Holy Spirit.
Isaac’s writings offer a rare example of a large corpus of ascetical texts written by an experienced hermit and is thus an important writer when it comes to understanding early Christian asceticism.[1
http://en.wikipedia.org/wiki/Isaac_of_Syria