IT is certainly an interesting, almost a sensational, thing that the discoverer of the quantum, which has done more than any other new theory in science to shake the old determmist philosophy, should be himself one of the stoutest to restate it in more guarded and acceptable terms. That is the gist of this small volume of essays by Max Planck, very carefully and clearly translated by Mr. W. H. Johnston. It is well worth reading for the calm and good judgment with which one of the acknowledged masters of modern science reviews both this determinist question and the other great cognate problems in contemporary scientific philosophy. The Philosophy of Physics By Max Planck. Translated by W. H. Johnston. Pp. 118. (London: George Allen and Unwin, Ltd., 1936.) 4s. 6d. net.