This selection of essays, book-reviews, broadcast talks and papers delivered to learned societies reflects the extraordinary breadth of Arthur Koestler's interests. From the trial of Galileo to the pleasures of canoeing down the Loire, from a detailed examination of the 'memory' of flatworms to an equally detailed examination of the futility of quarantining dogs, the author writes about a vast range of subjects which occupied his attention in the twelve years (1955-1967) covered by this collection. Those were the years that saw, among many other works, the publication of his great trilogy about the mind of man: THE SLEEPWALKERS, THE ACT OF CREATION, and THE GHOST IN THE MACHINE. It is not surprising therefore, that many of these essays elaborate certain aspects of arguments which occur in those books. They could, as the author says in his Preface, 'be called variations on certain themes', and the selection of books reviewed also reveals a certain thematic coherence. There is, however, a great deal of miscellaneous material, quite different in nature from Koestler's scientific preoccupations, with which he has been so closely associated in recent years. This includes the subjects of his 'crusades', such as the campaign for the abolition of hanging, the scandal of our quarantine laws, some escapist travel essays, and some controversies in which he became engaged. Like everything Koestler writes, DRINKERS OF INFINITY not only stimulates the mind, but gives the greatest pleasure to the reader while doing so.