Pythagoreanism stands as one the most influential – and obscure – philosophical movements in antiquity. Most ancients identified Pythagoras as the originator of the concept of philosophy, or “love of wisdom”; but his philosophy is often assumed to fade away with the dispersal of the Pythagorean communities in the fourth century BCE. This pathbreaking book presents the afterlife of Pythagoreanism, identifying the wide range of philosophical views that Pythagoreans developed in the Hellenistic and Roman periods, when the legacy of Pythagoras and his students was contested. Through careful analysis and synthesis of hundreds of ancient Greek passages never before translated into English, as well as extensive subject introductions, it gives shape to later Pythagorean philosophy as a whole, and in its parts, for the very first time.