“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