A comprehensive study of the cosmological doctrines of Abū Raihān Muhammad ibn Ahmad al-Bīrūnī,¹ undoubtedly one of the most learned of Muslim scholars and scientists, is a doubly difficult task because, on the one hand, in those of his works which are still in existence no attempt is made to deal with this subject thoroughly and systematically, and on the other, the philosophical works which he has written, in which he probably treated this subject more fully, are no longer extant.² In order to discover the conception which underlies his many studies of the manifestations of Nature it is necessary to assemble small bits from his works where he almost "accidentally" gives the reader a glimpse of some of the aspects of his conception of Nature. Yet, until some of his philosophical writings, like the Kitāb al-shāmil, or The Book of General Knowledge...