The Nature of Living Things: An Essay in Theoretical Biology is a 16-chapter text that describes the theory on the nature of life and mind. The first chapters cover first the microbiological aspects of living things, followed by intensive discussions on fundamentals of life, including information about DNA, RNA, cells, proteins, and the immune system. The succeeding chapters explore the concept of evolutionary development, the communication system in biology, plant biology, and the complexity of atom. The last chapters review the fundamental difference between the chemistry of life and the chemistry of the inorganic universe. This book is of value to biologists, evolutionists, and researchers who are interested in advancing their knowledge on nature of life.