This book covers the first 500 years of the common era. These years witnessed the revivals of Aristotelianism, Epicureanism, Pyrrhonism, Cynicism, and Pythagoreanism; but by far the most important movement was the revival of Platonism under Plotinus. Here, the historical context of Plotinus is provided including the currents of thought that preceded him and opened the path for him. The presuppositions of the Enneads are made explicit and the thought of Plotinus is reconstructed.

The author reorients the expositions of Middle Platonism and neo-Pythagoreanism. He provides a full exposition of Hermeticism and the doctrines of the Chaldean Oracles. He also defends the notion that Philo of Alexandria nourished a Jewish philosophy, not an eclectic mixture.