The decision to undertake this volume was made in 1971 at Lake Como during the Varenna summer school ofthe Italian Physical Society, where Professor Leon Rosenfeld was lecturing on the history of quantum theory. We had long been struck by the unique blend of epistemological, histori cal and social concerns in his work on the foundations and development of physics, and decided to approach him there with the idea of publishing a collection of his papers. He responded enthusiastically, and agreed to help us select the papers; furthermore, he also agreed to write a lengthy introduction and to comment separately on those papers that he felt needed critical re-evaluation in the light of his current views. For he was still vigorously engaged in both theoretical investigations of, and critical not reflections on the foundations of theoretical physics. We certainly did conceive of the volume as a memorial to a 'living saint', but rather more practically, as a useful tool to place in the hands of fellow workers and students engaged in wrestling with these difficult problems. All too sadly, fate has added a memorial aspect to our labors. We agreed that in order to make this book most useful for the con temporary community of physicists and philosophers, we should trans late all non-English items into English.

Inhalt
I / History of Science.- 1. On the Method of History of Science (1947).- 2. Science in History (Review of J. D. Bernal's Science in History) (1956).- 3. The Logical Problem of the Definition of Irrational Numbers (1927).- 4. Rationalism in Antiquity (1954).- 5. The Transformations of the Atomic Concept through the Ages (1969).- 6. Flicker in the Darkness (Review of Nicole Oresme and the Medieval Geometry of Qualities and Motions) (1969).- 7. Marcus Marci's Investigations of the Prism and Their Relation to Newton's Theory of Color (1932).- 8. Descartes at Uppsala (Review of R. Lindborg's Descartes i Uppsala) (1967).- 9. Newton and the Law of Gravitation (1965).- 10. Newton's Views on Aether and Gravitation (1969).- 11. The Genesis of the Laws of Thermodynamics (1941).- 12. Joule's Scientific Outlook (1952).- 13. An Analysis of Joule's Experiments on the Expansion of Air (1956).- 14. The Velocity of Light and the Evolution of Electrodynamics (1956).- 15. The Evolution of Oersted's Scientific Concepts (1970).- 16. The First Phase in the Evolution of the Quantum Theory (1936).- 17. Max Planck and the Statistical Definition of Entropy (1959).- 18. Matter and Force after Fifty Years of Quantum Theory (1963).- 19. Men and Ideas in the History of Atomic Theory (1971).- 20. Jacques Solomon (1959).- 21. Quantum Theory in 1929: Recollections from the First Copenhagen Conference (1971).- 22. Niels Bohr: An Essay Dedicated to Him on the Occasion of his Sixtieth Birthday. October 7, 1945 (1945; 2nd edition 1961).- 23. The Conception of the Meson Field: Some Reminiscences and Epistemological Comments (1968).- 24. Nuclear Reminiscences (1972).- 25. Celestial and Terrestrial Physics in Historical Perspective (1969).- II / Epistemology.- 1. On the Question of theMeasurability of Electromagnetic Field Quantities (with Niels Bohr) (1933).- 2. Field and Charge Measurements in Quantum Electrodynamics (with Niels Bohr) (1950).- 3. On Quantum Electrodynamics (Among Essays Dedicated to Niels Bohr on the Occasion of his 70th Birthday) (1955).- 4. On Quantization of Fields (1963).- 5. The Evolution of the Idea of Causality (1942).- 6. Strife about Complementarity (1953).- 7. Complementarity and Statistics, I and II (1958).- 8. Misunderstandings about the Foundations of Quantum Theory (1957).- 9. Foundations of Quantum Theory and Complementarity (1961).- 10. The Epistemological Conflict between Einstein and Bohr (Dedicated to Max Born on his 80th Birthday) (1963).- 11. Niels Bohr's Contribution to Epistemology (1963).- 12. The Measuring Process in Quantum Mechanics (On the 30th Anniversary of the Meson Theory by Dr. H. Yukawa, 1965) (1965).- 13. Statistical Causality in Atomic Theory: A General Introduction to Irreversibility (1972 and 1974).- 14. The Macroscopic Level of Quantum Mechanics (1972).- 15. Quantum Theory and Gravitation (1966).- 16. Questions of Method in the Consistency Problem of Quantum Mechanics (1968).- 17. The Method of Physics (1968).- 18. Some Reflections on Knowledge (1971).- 19. Epistemology on a Scientific Basis (1971).- 20. Condillac's Influence on French Scientific Thought (1972).- 21. Unphilosophical Considerations on Causality in Physics (1971).- 22. Irreversibility a Lay Sermon (On the Occasion of Professor K. Bleuler's Sixtieth Birthday) (1977).- 23. Berkeley Redivivus (Review of W. Heisenberg's Natural Law and the Structure of Matter) (1970).- 24. The Wave-Particle Dilemma (1973).- 25. A Voyage to Laplacia (1955).- III / Theoretical Physics.- 1. On the Energy-Momentum Tensor (1940).- 2. On theDefinition of Spin for a Radiation Field (1942).- 3. On the Behavior of a Canonical Ensemble during an Adiabatic Transformation (1942).- 4. On the Isolated and Adiabatic Susceptibilities (1961).- 5. On the Foundations of Statistical Thermodynamics (1955).- 6. Questions of Irreversibility and Ergodicity (1962).- 7a. Dynamical Theory of Nuclear Resonances (1968).- 7b. Coupling between Compound and Single-Particle Resonances (1968).- 8. The Structure of Quantum Theory (1968).- IV / Social Relations of Science.- 1. The Organization of Scientific Research (1948).- 2. The Atomic Researcher: The Atomic Physicist's Tasks, Goals and Methods (1968).- 3. Technical and Social Aspects of the Development of the European Scientific Research Organizations (1970).- 4. Social and Individual Aspects of the Development of Science (1971).- Bibliography of the Writings of Léon Rosenfeld.- Index of Names.