Introduction -- Ingredients of the Simplest Cells (Prokaryotes and the Sizes of their Contents) -- Bigger Cells (Eukaryotic Cells and their Contents) -- Hives of Industry (A Survey of Intermediary Metabolism) -- Delights of Transport (Mechanisms by which Cellular Contents are Moved around) -- As if Standing Still (Cellular Homeostasis and Regulatory Processes) -- Internal State and Gene Expression (Transcription and its Control) -- Sustaining and Changing the Internal State (The Interrelationship between Gene Expression and the Cell's Current Composition and Functional State) -- Responding to the Environment (Signal Processing and its Relationship to Cell Structure, Metabolism and Gene Expression) -- The Living State (A general characterization of 'life') -- Stability and Change in DNA (Why DNA is highly stable and a Survey of the Mechanisms by which it can Change) -- The Spice of Life (Variety, Habitats, Natural Selection, Symbiosis, Ecosystems) -- Curriculum Vitae (An Outline History of Life on Earth) -- The Origin of Life (Major Ideas and Unanswered Questions) -- Other Worlds (Ideas about Extraterrestrial Life, including a Critique of the Assumptions behind the 'Drake Equation' and the SETI Project) -- Intelligent Behaviour and Brains (The Meaning of 'Intelligence') -- Human Intelligence (Human Evolution and the Question of Human Uniqueness) -- Cells, Brains and Computers: towards a Characterisation of Mind -- Glossary -- Bibliography.