This book exhibits the richness and sophistication of Plotinian and Dionysian apophatic theologies by explicating their respective internal ""logics."" It articulates the unique metaphysical status and explanatory role that the One and God, respectively, play in Plotinus's and Dionysius's reflections, showing the way in which apophasis is generated and sustained by the metaphysical- explanatory lines of thought in which the One (Plotinus) and God (Dionysius) function as the ultimate, unconditioned source of everything else. In the context of explanation, negation serves to convey the incomparable reality of the One or of God as beyond being. However, the metaphysical and explanatory lines of thought are themselves situated within the