This volume offers the first critical edition and English translation of the Book of Physics of Barhebraeus' (d. 1286) magnum opus, Butyrum Sapientiae. Barhebraeus' text is not simply a Syriac translation of Aristotle or Avicenna; it offers some unexpected and un-Aristotelian views on time, motion, and inclination, thus adding various personal twists and turns to the work. For his Book of PhysicsBarhebraeus drew mainly on Arabic texts by Fakhr al-Din al-Razi, among them the as yet unedited al-Mulakhkha?, and maybe in some instances the lost al-Jawhar. There are also some remarkable similarities with the late Neo-Platonic philosopher Damascius (6th ct.), especially in Barhebraeus' treatment of time and motion, and also with Lucretius. Thus, the present volume argues, the Book of Physics was based on a variety of sources, which were re-arranged in a unique and very personal manner by Barhebraeus.