Roger Bacon's Philosophy of Nature. A Critical Edition, with English Translation, Introduction, and Notes, of De multiplicatione specierum and De speculis comburentibus (review)

586 JOURNAL OF THE HISTORY OF PHILOSOPHY a3:4 OCTOBER 1985 written form to the version which he presented in oral fashion on the second day of each disputation. Their brevity notwithstanding, many of the particular issues debated within Thomas's Quodlibets 1 and a are important, both because they reflect the concerns of those proposing questions to Aquinas, and because of the philosophical and theological precisions introduced by their author. Like most Quodlibets, they are remarkable for their range. Questions are disputed from the fields of speculative and moral theology, various parts of philosophy, sacramental theology, and canon law, to name some areas. Among issues of interest to students of medieval philosophy, mention should be made of Thomas's treatment of the then hotly contested question of unicity vs. plurality of substantial form in individual substances, especially human beings, and the theologically related question concerning the numerical identity of the body of Christ during the period in the tomb (Quodlibet 1, qu. 4, art. 1; Quodlibet 2, qu. l, art. 1). Considerable attention is directed to questions about created separate substances (angels): for instance, the manner in which they may be said to be in place (Quodlibet l, qu. 3, art. 1); or whether such beings can pass from one place to another without going through an intermediate place (art. 2). Also immediately directed to angelic beings, but much broader in metaphysical application are two other questions: whether an angel is composed of essence and existence (esse);and whether supposit (or first substance) and nature are one and the same (Quodlibet 2, qu. 2, Ha. 1 and 2). In answering the first Thomas also offers important precisions concerning his understanding and application of the metaphysics of participation. In Quodlibet 2, qu. 3 there is an interesting comparison and contrast between the time of material beings and that of spiritual creatures. Among more practical questions, Aquinas was asked whether the children of Jewish parents should be baptized against the will of their parents (Quodlibet 2, qu. 4, a. 2), and whether a seller is bound to tell a buyer about a defect in an item being sold (qu. 5, art. 2). Thomas says "no" to the first, and distinguishes in replying to the second. All in all, the translation reads smoothly. While some readers may not agree with certain choices of English equivalents for technical Latin expressions, this is a minor point and does not detract from the general reliability of the translation as verified by a spot-check. It is to be hoped that the remainder of Aquinas's Quodlibets will eventually be made available in English. JOHN F. WIPPEL The Catholic University of America David C. Lindberg, editor and translator. Roger Bacon's Philosophy of Nature. A Critical Edition, with English Translation, Introduction, and Notes, of De multiplicatione specierum and De speculis comburentibus. New York: The Clarendon Press, Oxford University Press, 1983. Pp. lxxxi + 42o. $84.oo. For such disparate modern philosophers as Descartes, Newton, and Locke, the optical concerns of the geometry and physics of light still lay not at the periphery but at the nexus of natural philosophy and epistemology. This was among the unac- BOOK REVIEWS 587 knowledged debts owed to the medieval "perspectivists," especially Roger Bacon (ca. 1~2o-1292 ). This English Franciscan believed that the investigation of vision disclosed the ties binding psychology, epistemology, and semantics (as effects) to the natural causation processes, chiefly the propagation of light. Bacon struggled throughout the 126os to work out his views, producing a series of philosophically significant but uneven treatises. Two of the most important, De multiplicatione specierum (On the Multiplication of Species) and De speculi~ comburentibus (On Burning Mirrors), are here edited and translated by the scholar most conversant with the entire perspectivist tradition, David Lindberg. He argues that "it was by no means obvious, until Bacon made it obvious, precisely how light is propagated, For example, how could one know whether a luminous source radiated as a whole or as a collection of parts?" (lxxiii) For Lindberg, Bacon's recognition and consideration of such problems in De speculis yielded "the most incisive and original piece of geometric optics produced in the West during the...