Fully 180 of this book's 390-page text are given to a history of space exploration--a subject the author has dealt with in earlier books. Another 40 pages go to the exploration of the Southern seas and Antarctica, which again the author has dealt with previously. The preceding 60 pages cover the history of earlier exploration from Erik the Red through Drake. Where space permits, Lewis provides detailed, meaty accounts covering everything from the economics of funding to the scientific lessons learned and distinguished by the qualities which won his earlier books so good a reception. A rationale for this new book is spelled out in the introduction and repeated from time to time. It is a preoccupation with the motivation for all this arduous endeavor: ""deadly competition among men and families for land, among nations for power and wealth."" There is no need, Lewis insists irritably, to postulate an innate biological compulsion to explore. But his theory seems to be only a partial explanation of his compelling narratives, and indeed sounds almost extraneous to them. What, for example, of the cooperative elements in the International Geophysical Year and the independent, hobby-like beginnings of rocketry in the US, Germany, and Russia which he describes? A whole that is less than the sum of its parts.