Jacob al-Bartilli, also known as Jacob bar Shakko, was an important Syrian Orthodox scholar of the thirteenth century (d. 1241). Hailing from the town of Bartilleh, near Mosul, he was the student of the East Syrian John bar Zo‘bi as well as the Muslim Kamal al-Din b. Yunus al-Mawsili before becoming the Bishop of Mar Mattai and Azerbaijan in 1232, taking Severos as his episcopal name. Among the works Jacob has left us is this theological treatise, entitled The Book of Treasures, which has here been translated in its entirety into Arabic. The text is divided into four parts, covering the Holy Trinity, the Incarnation of the Word, Divine Providence (which deals in part with the problem of evil) and finally the Creation of the World, the Resurrection and the Final Judgment. In each section, Jacob treats his subject in a thorough and systematic way and the text is of great interest to historians, theologians, and philosophers as well as laymen. The Syriac text remains unpublished and this Arabic translation has been executed by the Deacon Behnam Daniel al- Bartilli on the basis of three different manuscripts. An introduction by Bishop Gregorios Yohanna Ibrahim provides helpful information on the life and works of Jacob al- Bartilli. The Book of Treasures will prove essential reading for scholars seeking to understand the texture of Christian thought in the thirteenth-century Middle East.