Our sense of smell, as Trygg Engen reminds us early in this definitive work, has been neglected as a research area. This neglect bellies the very critical role that the sense plays in human adaptation to the environment through the monitoring of odors. Smell is "learned" through experience and results, Engen maintains, in a schema of memory system that enables individuals to process and categorize odors. There are closer relationships between the individual detecting an odor, the circumstances or similar odors, memory will bring back the early experience and directly affect the reaction to the new stimuli. Engen sees odor perception as mainly psychological, unlike the traditional approach which sees the sense larely as an innate mechanisms with a direct physiological basis. The research underlying this book is the most current in sensory cognition, reminding the reader of the importance of the sense of smell through examples of what deprivation entails. The author develops an appreciation of the odor-sensing ability mankind has and explores the uses to which that sense is applied. The ability to relate past to present perception - odor memory - and the gradation of odor impact are discussed, as well as the engaging questions of fragrances effects on behaviour, odors and sexuality, mother-infant bonding and pollution.