The essays in this volume, structured like a small dictionary, investigate some themes philosophically relevant to the public sphere, such as: common sense, death, individuation, liberty, public/private, responsibility, secularisation, social justice, work. They explore some philosophical lines of thought, some paths, within that sphere, which inevitably cross one another, from one essay to the next. Their aim is to show the relevance of philosophical reflection on the public sphere - the place in which philosophy ultimately finds its historical a priori and its very reason for being. Gaetano Chiurazzi is Professor of Philosophy at the University of Turin. Davide Sisto is Research Fellow at the University of Turin. Soren Tinning is a Ph.D. student at the University of Turin.