What strikes one first about two recent books in philosophy of science is that they seem to be polar opposites in all important respects. Bridgman, of course, typifies the hard-headed and skeptical physical scientist, whose interest in the broad “philosophic” questions of scientific methodology stems largely from current problems in theoretical physics, but he is, nevertheless, very much concerned to extend the salutary effects of operational analysis to other intellectual disciplines. Jung, on the other hand, not only is a psychiatrist—and therefore professionally committed to a certain gullibility about mental phenomena—but he also is deeply convinced of the importance for science of such subjects as astrology and alchemy; and Pauli, although a distinguished physicist in his own right, has clearly been influenced by Jung's conception of archetypal ideas in the collective unconscious.