The mind-body problem is the ultimate intractable enigma. How can we - being complex physical systems - have multicoloured experiences, and make conscious choices? This book proposes that all fundamental constituents of the universe are agents, which perceive one another, and freely act according to their percepts. Contemporary science can be explained in entirely mentalistic terms. This is consistent with many interpretations of quantum mechanics, such as GRW and Roger Penrose's OR theory.