Trying to summarise the history of an extraordinarily complex system of occult sciences is difficult, but Goodrick-Clarke has made a remarkably successful job of it. Magic in its various forms and esoteric exploration of non-material planes of existence are actually uneasy bedfellows with astrology and alchemy whose investigations primarily concern the material world, even if certain aspects of both take in and can be applied with the help of states or entities beyond the material, and so perhaps it is not surprising that neither astrology nor alchemy plays more than a minor role in Goodrick-Clarke's narrative. What we are given, however, is a succinct but always comprehensible account of the way in which western intellectuals have perceived, considered, explored, used and abused the notion of and belief in the existence of interconnecting worlds from the early centuries ad to the present day. Thus, Neoplatonism, Kabbalah, ritual and angelic magic, Boehmism, Rosicrucianism, the Illuminists, Swedenborg and Theosophy receive their due meed of attention, ending with a review of the various ways in which esotericism has sought to befriend the physical sciences and thus to some extent re-sacralise a world which the nineteenth and twentieth centuries had hoped to disenchant once and for all. Each chapter is accompanied by a list of books and articles for further reading, all very helpful. Books in languages other than English are included, always a good sign that an author has been able and willing to broaden his or her horizons and introduce readers to a broad range of relevant scholarship. One slight disappointment in the book comes from the weighting of its historical periods. Just over half is devoted to the period between the eighteenth century and the present day, which means that, while earlier chapters on the Renaissance, sixteenth and seventeenth centuries are very well done, they receive shorter measure, and although it is true that a study of the later period serves as a reminder that esotericism did not disappear or even fade away as the physical sciences grew to exert a dominant influence, the late medieval and early modern centuries were those in which esotericism was at its most vibrant, competing, as it were, with religion and physical science for serious intellectual attention. The Middle Ages, too, are glossed over and this is undoubtedly a weakness in the treatment of the subject. Nevertheless, what Goodrick-Clarke does, and he does a great deal, is very well done indeed and this study should be on every historian's bookshelf.