This book seeks to answer the question What is holiness? What do we talk about when we talk about holiness? We might describe many things as holy but as Socrates says what is the essential aspect by which all holy acts are holy? Sanctum Sanctorum gives an account of the holy from within the Christian participatory tradition and argues that holiness is included in a special category of divine names that Christian metaphysics calls transcendentals (which are five: being one truth goodness and beau