Filling the void in the current scholarship, Giannis Stamatellos provides the first book-length study of the Presocratic influences in Plotinus' Enneads. Widely regarded as the founder of Neoplatonism, Plotinus (204-270 AD) assimilated eight centuries of Greek thought into his work. In this book Stamatellos focuses on eminent Presocratic thinkers who are significant in Plotinus' thought, including Heraclitus, Parmenides, Empedocles, Anaxagoras, the early Pythagoreans, and the early Atomists. The Presocratic references found in the Enneads are studied in connection with Plotinus' fundamental theories of the One and the unity of being, intellect and the structure of the intelligible world, the nature of eternity and time, the formation of the material world, and the nature of the ensouled body. Stamatellos concludes that, contrary to modern scholarship's dismissal of Presocratic influence in the Enneads, Presocratic philosophy is in fact an important source for Plotinus, which he recognized as valuable in its own right and adapted for key topics in his thought.