The work offers a comprehensive study of old age and death, treating senescence as a distinct life stage and distinguishing early senescence from later senectitude. Drawing on physiology, psychology, historical and cross-cultural evidence and the author's own reflections, it surveys attitudes toward aging, subjective experiences of isolation and individuation, bodily and mental changes, and social roles and responsibilities for older adults. It advocates preparing for late life, developing a scientific gerontology, and recognizing the needs and potential functions of mature persons while combining empirical review with personal observation.