The Syriac treatise published in the present volume is in many respects a unique text. Though it has been preserved anonymously, there remains little doubt that it belongs to Porphyry of Tyre. Accordingly, it enlarges our knowledge of the views of the most famous disciple of Plotinus. The text is an important witness to Platonist discussions on First Principles and on Plato's concept of Prime Matter in the Timaeus. It contains extensive quotations from Atticus, Severus, and Boethus. This text thus provides us with new textual witnesses to these philosophers, whose legacy remains very poorly...