In 2021, a previously unknown treatise by Porphyry of Tyre, which has been preserved in a Syriac translation, was made available to historians of philosophy: Porphyry, On Principles and Matter (De Gruyter, 2021). This text not only enlarges our knowledge of the legacy of the most prominent disciple of Plotinus but also serves as an important witness to Platonist discussions of first principles and of Plato’s concept of prime matter in the Timaeus. The aim of the present volume of collected studies is two-fold. On the one hand, it brings up an update to the state of the art of our knowledge of Porphyry’s philosophy and of his role in the transmission of the earlier philosophical materials, especially those of the Middle Platonic works. On the other hand, it focuses on the questions of the reception of Porphyry’s legacy, both by Greek and Latin Platonists (with special interest in Calcidius) and by Christian Oriental authors (with particular focus on the Syriac tradition). The primary audience of the book will be scholars and graduate students in ancient and late ancient Greek philosophy, Orientalists and scholars interested in the Christian reception of Greek philosophy, in the studies of the Christian Orient, as well as in Greek, Latin, and Syriac philology.