1. Origins - Chapter One: Atoms; Waves; Quanta; Before and after Democritus; Titus Lucretius Carus; Isaac Newton on atoms. Chapter Two: Spectra; Ions; Radiant matter; Atoms, electrons, waves; Discovery of spectral analysis; The beginnings of television; William Crookes; Kinetic theory of gases; Mikhail Vasilyevich Lomonosov. Chapter Three: The planetary atom; Spectral series; Photons; Victory of atomistics; The indivisible atom; The diffraction grating; Just what hath Rutherford wrought? Light pressure; Chapter Four: Pre-Bohr times; The Bohr atom; Post-Bohr times; Formal model of the atom; Niels Henrik David Bohr; Experimental proof of Bohr's postulates. Chapter Five: Teachings of the Ancients; First attempts; Elements and atoms; Table of elements; The Periodic law; Atoms and people. 2. Ideas - Chapter Six: Contemporaries comment on Bohr's theory; Phenomenon, image, concept, formula; Heisenberg's matrix mechanics; The foundation of physics. Chapter Seven: Louis de Broglie; Matter waves; Optical-mechanical analogy; Schrodinger's wave mechanics; The life of Boscovich ... ... and his atom; Paul Ehrenfest (1880-1933). Chapter Eight: Schrodinger's equation; The meaning of the psi function; The image of the atom; Quantum truth; Compton's experiment; Electron diffraction. Chapter Nine: Wave-particle duality; Uncertainty relation; Complementarity principle; Duality and uncertainty; Poets and the complementarity principle. Chapter Ten: Heads or tails and target shooting; Electron diffraction; Probability waves; Electron waves; The atom and probability; Probability and atomic spectra; Causality and chance, probability and certainty; People, events, quanta. Chapter Eleven - What is an atom? What is quantum mechanics?; Physical reality; In search of the last concepts. 3. Results - Chapter Twelve: Wilhelm Konrad Rontgen; Antoine Henri Becquerel; Pierre and Marie Curie; Ernest Rutherford and Frederick Soddy; The energy of radium; X-ray waves. Chapter Thirteen: The chemisty of radioelements; Isotopes; uranium family; Stable isotopes; Radioactive decay energy; Nuclear binding energy; Uranium; Earth and radium; Knights of the fifth decimal place. Chapter Fourteen: Probing into the nucleus; The neutron; Artificial radioactivity; Slow neutrons; Nuclear fission; Letters about fission. Chapter Fifteen: Tunnel effect; Effective cross-sections of reactions; Neutron cross-sections; Nuclear fission; Labelled atoms; Radiocarbon dating. Chapter Sixteen: Chain reaction; Nuclear reactor; Spontaneous fission of uranium; The natural nuclear reactor at Oklo. Chapter Seventeen: Atomic Energy; Plutonium; The atomic bomb; The atomic problem; A chronology of the atomic era; Soddy on atomic energy. Chapter Eighteen: Solar light; Crucibles of elements; The fate of the Sun; The Sun, life and chlorophyll; Life under the Sun; A sun on earth; Quanta around us. 4. Reflections - Chapter Nineteen: Inception of the scientific method; Essence of the scientific method and its development. Truth and completeness of the scientific picture of the world. Science and humanity; Boundaries of the scientific method; Science and art; Future of science; Epilogue.