“You’re not a painter if you haven’t painted gray”, declared Paul Cézanne. The same could be said of philosophers: you’re not a philosopher if you have never thought gray. This simple four-letter word signifies much more than a quasi-neutral color lying between black and white: we use the same word to describe moods, November skies, the hair of the elderly, the withered features of faces, dusty shelves, faceless bureaucracies, dreary politicians and hundreds of other things. This plain, unassuming word conceals a multitude of thoughts that we seldom pause to consider. In this exceptionally original book, Peter Sloterdijk follows the grey thread through the history of philosophy, art, literature and politics, enabling us to see familiar things in new ways and highlighting features of our lives that would otherwise remain unseen. Beginning with Plato’s allegory of the cave which introduced the concept of gray into thought, Sloterdijk unfolds a chiaroscuro narrative which recognizes the power of grey as a metaphor for the indefinite, the indifferent, the ordinary, the intermediate and the neutralizing. We see the invention of photography and monochrome’s journey through modern art - from Malevich’s _Black Square_ to Richter’s grey panel paintings - in a new light, and we see modern states and modern politics as full of grey zones, from the hidden spheres of the security services to the extraterritorial spaces that harbor illegal activities like money laundering and the drug trade. A work of brilliance by one of the most creative philosophers writing today, _If You Have Never Thought Gray _will appeal to a wide readership interested in philosophy, art and politics, and to students and academics in philosophy, visual arts and the humanities generally.