This work applies scientific methods to questions of life, sex, death, and human constitution, arguing that health depends on harmony between organism and environment. It surveys the roles of microbes, circulating white blood cells, and bodily fluids in infection, inflammation, and aging, describes mechanisms such as phagocytosis and directed migration of immune cells, and links microbial interactions to senescent changes. It examines reproductive disharmonies and their social implications, critiques evasive doctrines, and proposes a research programme aimed at strengthening natural defences and improving human well-being with measured optimism.
