In the letters contained in this book, David Bohm argues that the dominant formal, mathematical approach in physics is seriously flawed. In the 1950s and 60s, Bohm took a direction unheard of for a professor of theoretical physics: while still researching in physics, working among others with Yakir Aharanov and later Jeffrey Bub, he also spent time studying “metaphysics”—such as Hegel’s dialectics and Indian panpsychism. 50 years on, questions raised about the direction and philosophical assumptions of theoretical physics show that Bohm’s arguments still have contemporary relevance.