This book explores how introductory methods shaped school practice and intellectual activity in various fields of thought of the Early Imperial Age and Late Antiquity. The isagogical crossroads—the intersection of philosophical, philological, religious and scientific introductory methods—embody a fascinating narrative of the methods regulating ancient readers' approach to authoritative texts and disciplines. The strongly innovative character of this book consists exactly in the attempt to explore isagogical issues in a wide-ranging and comprehensive perspective—from philosophy to religion, from medicine to exact sciences—with the aim of detecting connections, reciprocal influences, and interactions shaping the intellectual environment of the Early Imperial Age and Late Antiquity.