BOOK REVIEW DANIEL DANIN, PROBABILITIES OF THE QUANTUM WORLD, Mir Publishers, Moscow, 1983, pp 269. IN THE YEAR 1900 when classical physics could well feel complacemt for having provided explanations for the physical phenomena in terms of elegant mathematical equations, one of its ablest exponents, Max Planck, dealt it a severe blow with far reaching implications with which he himself could never reconci-le. On December 14, 1900, Plank reported to a meeting of the Berlin Academy of Sciences Physical Society on his attempt to overcome one of the difficulties of the theory of thermal radiation. Planck's postulate, blasphemous for the classical religiosity to which he adhered, was that energy is absorbed and emitted in bundles as against the continuous transfer assumed in classical physics. This seminal idea of energy packets marked the beginning of a revolution of unprecedented magnitude in physics. In a short period of three decades thereafter, the edifice of quantum mechanics was built, in which scientists from all over the world participated. Damn's book is a facsinating account of this most turbulent revolution in the history of natural sciences which is told not in a logical order but "as a mixture of ideas and passions, moments of inspiration and despair, joy and sadness...". The book is based on the rich material available in the archives of Bohr Institute of Theoretical Physics in Copenhagen, the capital of the quantum revolution. In 1960 a project was conceived to collect live records of the participating scientistis9 recollections of the high drama between the period 1898 and 1932 "without parallel in the last three hundred years". Headed by Thomas Kuhn, a competent team of researchers took 175 interviews between 1962 and 1964. Under the project, recollections of Enrico Fermi (d. 1954), Albert Einstein (d. 1955), John von Neumann (d. 1957), Wolfgang Pauli (d. 1958), Abram lofTee (d. 1960) and Erwin Schrodinger (d. 1961) could not be recorded, but it contains 12 interviews by Heisenberg, five each by Bohr and Dirac, three each by Bohr and Oppenheimer, etc. From hindsight, the development of scientific theories and therefore the histoiy of scientific congnition appears to be a smooth cumulative process. However, the actual struggle waged by the participants with their prejudices, clash of opinions requiring the boldness bordering on madness and the interplay of creative imagination and hard facts, make one realise that underneath the process of development of science