The third in a series that began with Descartes" Error, this book deftly combines recent advances in neuroscience with charged meditations on foundational 17th-century philosopher Baruch Spinoza, and the result is Damasio"s fullest report so far on the nature of feelings. A Salk Institute professor and head of the department of neurology at the University of Iowa Medical Center, Damasio makes a useful distinction between emotions, which are publicly observable body states, and feelings, which are mental events observable only to the person having them. Based on neuroscience research he and others have done, Damasio argues that an episode of emoting begins with an emotionally "competent" stimulus (such as an attractive person or a scary house) that the organism automatically appraises as conducive to survival or well-being (a good thing) or not conducive (bad). This appraisal takes the form of a complex array of physiological reactions (e.g., quickening heartbeat, tensing facial...