This volume studies the origin and evolution of philosophical interest in Aristotle’s Categories. After centuries of neglect, the Categories became the focus of philosophical discussion in the first century BCE, and was subsequently adopted as the basic introductory textbook for philosophy in the Aristotelian and Platonic traditions. In this study, Michael Griffin builds on earlier work to reconstruct the fragments of the earliest commentaries on the treatise, and illuminates the earliest arguments for Aristotle’s approach to logic as the foundation of higher education. Griffin argues that Andronicus of Rhodes played a critical role in the Categories’ rise to prominence, and that his motivations for interest in the text can be recovered. The volume also tracks Platonic and Stoic debate over the Categories, and suggests reasons for its adoption into the mainstream of both schools. Covering the period from the first century BCE to the third century CE, the volume focuses on individual philosophers whose views can be recovered from later, mostly Neoplatonic sources, including Andronicus of Rhodes, Eudorus of Alexandria, Pseudo-Archytas, Lucius, Nicostratus, Athenodorus, and Cornutus.