The work examines the nature and origins of feelings by contrasting intellectualist accounts with a physiological perspective that roots emotions in bodily impulses, organic sensibility, and unconscious processes. It opens with general analysis of pleasure, pain, and the defining features of emotional states, then considers emotion as a complex psychic function. The second part surveys particular emotions in their development, social expression, and pathology, using comparative and genetic approaches to trace transformations and verify principles. Methodological limits of introspection and experiment are acknowledged while emphasis is placed on biological foundations and historical evolution of affective life.