Foreword; Part I. Nature and the Greeks: 1. The motives for returning to ancient thought; 2. The competition, reason v. senses; 3. The pythagoreans; 4. The Ionian enlightenment; 5. The religion of Xenophanes, Heraclitus of Ephesus; 6. The atomists; 7. What are the special features? Part II. Science and Humanism: 1. The spiritual bearing of science on life; 2. The practical achievements of science tending to obliterate its true import; 3. A radical change in our ideas of matter; 4. Form, not substance, the fundamental concept; 5. The nature of our 'models'; 6. Continuous descriptions and causality; 7. The intricacy of the continuum; 8. The makeshift of wave mechanics; 9. The alleged break-down of the barrier between subject and object; 10. Atoms or quanta - the counter-spell of old standing, to escape the intricacy of the continuum; 11. Would physical indeterminacy give free will a chance? 12. The bar to prediction, according to Niels Bohr; Literature.