Preface.- Acknowledgements.- List of Abbreviations.- Chapter 1. 1900-1962. From Planck to Bohr.- Chapter 2. 1913. "On the Constitution of Atoms and Molecules": Quantum Jumps and Epistemological Leaps.- Chapter 3. 1925. "Atomic Theory and Mechanics": From the Old Quantum Theory to Heisenberg's Quantum Mechanics.- Chapter 4. 1927. "The Quantum Postulate and the Recent Development of Atomic Theory" (The Como Lecture): Complementarity vs. Causality.- Chapter 5. 1929. "The Quantum of Action and the Description of Nature": New Complementarities and a New Interpretation.- Chapter 6. 1931. "The Space-Time Continuity and Atomic Physics" (the Bristol Lecture): Quantum Phenomena and the Double-Slit Experiment.- Chapter 7. 1933. "On the Question of Measurability of Electromagnetic Field Quantities": Complementarity and Quantum Field Theory.- Chapter 8. 1935. "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?": The EPR Experiment and Complementarity.- Chapter 9. 1937-1938. "Complementarity and Causality" and "The Causality Problem in Atomic Physics" (The Warsaw Lecture): The Knowable and the Unthinkable.- Chapter 10. 1954-1962. "The Unity of Knowledge": New Harmonies.- Bibliography.- Name Index.- Subject Index.