Ancient Greek philosopher Epicurus provided some of our most cherished assumptions about physics and ethics. He postulated an infinite universe made exclusively of atoms and void. He also treated slaves and women as equals and defined our standards of pleasure and luxury. Now David Swift turns to Epicurus for help with another significant mystery: the scientific explanation of mind. Using Epicurean ideas that our minds are in our chests and, perhaps even more radically, that meaning is understood in our sense organs he re-examines and reinterprets the works of philosophers like Descartes, Locke, Kant and Mill and scientists such as Pavlov, Freud, Skinner and Rogers. Seen in the light of the Epicurean concept, Renaissance philosophy and classic scientific psychology validate a surprisingly consistent and coherent scientific explanation of behaviour. The mechanisms of meaning, knowledge, learning and remembering are explained in terms of biological reflexes. The secrets of love, hate and loyalty are revealed as non-verbal knowledge only accessible as feelings. And success, failure, criminal and other behaviours are shown to be the results of learned experience not genetic predisposition. At last we have the possibility of a plausible biologically-based general psychological theory.