Being Is At The Forefront Of Philosophical Debate From Its Very Beginning, Whereas Non-being Is Often Considered As A Derivative Of Being And An Obstacle For Thought. Yet, As This Book Argues, Non-being Is Crucial For The Constitution And Understanding Of Being, Without Which Being Can Neither Be Nor Thought. The Monograph 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. Most Contemporary Studies Of Ontology In Antiquity Are Dedicated To Being In Its Philosophical And Philological Significance. However, The Book Shows That Ancient Thinkers Argue For The Centrality Of Non-being In The Understanding Of Being. Because Non-being Is Not, And Thus Cannot Be Thought On Its Own, It Needs A Special Philosophical Apparatus And Language For Its Investigation And Expression-- Provided By Publisher.