Being has been at the forefront of philosophical debate from its very beginnings, whereas non-being has been considered derivative of being and an obstacle for thought. Dmitri Nikulin argues that without non-being, being can neither be nor thought. This book provides a critical, historical, and systematic reconstruction of the concept of non-being in ancient philosophy, from Pre-Socratic thought to Neoplatonism, in the works of Parmenides, Democritus, Plato, Diogenes, Aristotle, Plotinus, and Simplicius.