Correspondance du P. Marin Mersenne

Correspondance du P. Marin Mersenne, ed. by PAUL TANNERY and CORNELIS DE WAARD, Volume III (1631-1633), 2nd ed., Paris, editions du Centre National de la Recherche Scientifique, 1969, pp. xiv, 660, illus., 120F. The correspondence of Mersenne (1588-1648) antedates and practically anticipates the monumental collections of scientific work given in the second part of the century in the Transactions of the Royal Society, the Journal des Savants and the Acta Eruditorum. It surpasses the latter in the extent and intimacy of personal information which can be derived from it. It concerns the great luminaries of the time such as notably Galileo, Gassendi and Descartes. With the exception of some light thrown on Descartes' early acquaintance with Harvey's discovery, there is nothing of immediate interest to the medical historian. What does concern him, however, in the volume under notice, are the eleven letters from the pen of Jean-Baptiste Van Helmont. From these we get first-hand insight into all the aspects of his work and thought-the purely scientific and medical as well as the religious, metaphysical and mystical aspects. What is more, we clearly see how they were deeply interlocked and integrated. This is a lesson for the historian of science who is inclined to forget that in the past, scientific discovery was compatible with, and indeed inspired by, non-scientific motives and thoughts. Even more so, it should demonstrate the absurdity of the amusing idea that no scientific advance or for that matter philosophical sense could be expected or worth mentioning with reference to a mind given to religious belief and mystical contemplation, in the seventeenth century. At all events Mersenne, the rationalist 'Christian philosopher' and Aristotelian, the advanced mathematician and keen enquirer into physical phenomena and theories, sought his advice and opinion. He cultivated his friendship in significant contrast to Robert Fludd whose cosmosophical speculations and largely inept mechanical devices were equally distasteful to Mersenne as they were to Kepler, Gassendi and Van Helmont. In Van Helmont Mersenne seems to have recognized and esteemed a congenial truly scientific observer and religious naturalist philosopher. On the scientific side, perhaps the most revealing item in the Helmont letters is the repeated discussion of the properties of air and its significance in life-ideas that sound strangely akin to a presentiment of oxygen. In view of all this, the apologies offered for the existence of these letters in a volume largely concerned with scientific news sound odd. But full credit must be given to the editors and the reviser for the wealth of learned comments and notes to each of the 111 letters contained in this second edition of the third volume of letters. Indeed, each of them presents a dissertation in its own right which is indispensable for the student of the scientific world of perhaps the most important period in its development. WALTER PAGEL