Biology on the nature of life: is life a machine or something more? This classic lecture surveys what biology seeks to explain, from living processes to evolution, and tests how far a physical and chemical view can take us. This edition gathers the author’s account of how biology divides into structure and function, how mechanistic ideas have guided research, and where vitalist thoughts still arise. It also shows how Mendelian heredity offers a concrete, testable mechanism behind inherited traits, while tracing debates about life’s origin and the role of evolution. Why biologists treat life as both a machine and a system of adaptations. How historical thinkers like Descartes, Kant, and Huxley shaped major views of life and mechanism. How Mendel’s laws enable quantitative predictions in heredity. Why the mechanistic view remains a practical working program, despite unresolved questions. Ideal for readers curious about early 20th‑century biology, evolution, and the debates shaping how we understand living systems.