I have gone in for Lewis studies since encountering his Ransom trilogy in an undergraduate seminar in the late 1970s. Over the years, I have collected most of the author's published writings in every genre he attempted, and have read numerous books and articles on his life and work, as well as on various of his colleagues and inspirations. PLANETS IN PERIL may be the best critique I have come across, and if one could own only two secondary sources in the field I would recommend this and the biography by Green and Hooper. What makes Downing's volume so remarkable is chiefly its sheer comprehensiveness. Despite the focus of its sub-title, the book manages to draw in extraordinarily illuminating references to nearly every other work in the Lewis canon, showing through them far more of the man's Christian, mediaeval, and poetic world view than one would expect to be relevant. I had thought myself to have a good grasp of the celebrated Oxford don and Cambridge professor, yet this book increased my understanding manyfold. I also appreciated Downing's objective balance. Without shying away from what he feels are Lewis's limits or flaws, he does better than I have yet found in vindicating the man against many of the stock objections that have long been levelled at him. A recurring argument throughout is that the trilogy is best understood less in the framework of science fiction than in light of its author's expertise in and love for the literature and motifs of the mediaeval and Renaissance eras. Lewis was not so much a mythmaker as a '"re-mythologizer", one who takes old myths ... and revitalizes them'; and Downing perceives him as having done something similar with old VALUES -- ones fallen out of fashion yet which seemed to him worth recapturing.