Sirach (Ecclesiasticus): Wisdom Rooted in Covenant. The Book of Sirach—also called Ecclesiasticus or The Wisdom of Jesus Son of Sirach—is one of the great treasures of the Bible of the Early Church. Written around 200–175 BC, it bridges the Hebrew wisdom tradition with the world of the New Testament. For centuries it was considered Scripture by Jews and Christians alike, though most Protestant Bibles now omit it.