The phrase "on historical principles" might well have been added to the titles of these volumes, for most sections are presented historically-much too historically in some cases. For instance, the section on mechanisms of evolution proceeds from Cuvier and Lamarck to Darwin, Wallace, and Huxley, and then concludes with the Scopes trial. If anyone wishes to know current concepts of evolutionary mechanisms, he won't find them here. Isaac Asimov is Associate Professor of Biochemistry at Boston University and has produced 767 pages of well-written text plus nearly a hundred pages of bibliography, credits for illustrations, and an index. The first volume discusses the physical and the second, the biological sciences. Within each volume the organization is not patterned on standard basic texts but is enriched with imagination. And Asimov does write well. However, he has attempted to cover more material than 767 pages can contain. The publisher describes the book as "written for the layman and for the specialist as well." Only occasionally will the specialist experience anything other than frustration in using these volumes. The work will be of interest to those who know little or nothing of science, but they will not always be introduced to current science.