Also known as Isaac of Ninevah, he was born in Arabia in the early 7th century. As a young man he entered a monastery and devoted himself to the monastic life.
Later in his life, he was ordained Bishop of Nineveh in the north of modern Iraq. After just five months, he resigned as bishop because his duties conflicted with his asceticism. He withdrew to the wilderness. In deep old age, he retired to the monastery of Shabar, where he reposed at some 90 years of age.
Saint Isaac's extensive writings and homilies have survived to the present day, and his influence on Eastern especially monasticism are strong. He emphasizes mystery and the power of the Holy Spirit. His feast is celebrated on January 28.