Roger Bacon and the origins of Perspectiva in the Middle Ages

The bibliographic details will convince any well-educated historian that this book should be available in all good libraries. So indeed it should. The advent of microfilm has helped the editor to make full use of many more manuscripts than his predecessors, with consequent benefit to the authority of the resulting text. Roger Bacon's treatise, which David Lindberg, following a "guess" by Stewart Easton, dates to about 1263 (p. xxiii), is a foundation text for the science of perspectiva as it was understood in the following three centuries or so. The author explicitly identifies many of his sources, for instance Aristotle and several commentators, Avicenna, Constantine (that is Constantine the African, the translator of Hunayn's On the eye, whom Roger Bacon mistakenly supposes to be its author), Euclid and Alhacen. (Lindberg makes a straightforward case for the spelling Alhacen: it is found in the majority of the manuscripts. The form "Alhazen" marks the influence of the spelling adopted in Friedrich Risner's edition of 1572.) Some mentions of "the physicians" are explained in the notes (pp. 341-92) as references to Galen, but as the index does not cover the notes the passages can be retrieved only through the Introduction. Since this book includes a translation, its users will very probably include newcomers to the subject. They would run into problems if they simply started with the Introduction. Understandably fed up with being regarded as experts on the boring intermission between Antiquity and the Renaissance, some earlier medievalists made what now seem to be exaggerated claims alleging similarities between the role of experiment in the work of (among others) Roger Bacon and Galileo Galilei (1564-1642). Deploying the levelheaded scholarship familiar to readers of his numerous earlier publications on medieval optics, Lindberg is polite but firm in dealing with such claims; however, newcomers may not understand why some of this needs to be said. Further, the account of later developments is too brief to be helpful. For instance, fifteenth-century authors listed as having read Roger Bacon are provided only with dates of death, though for many, such as Lorenzo Ghiberti (1378-1455) and Leonardo da Vinci (1452-1519), dates of birth are also known; and there is no explicit acknowledgement that it is generally highly uncertain how any debt is to be apportioned between Roger Bacon himself and his sources. For example, it has been proved conclusively that Lorenzo Ghiberti made use of a thirteenth-century vernacular translation of Alhacen (see G Federici-Vescovini, 'I1 problema delle fonti ottichi medievali del Commentario terzo' in Lorenzo Ghiberti nel suo tempo, Florence, 1980, pp. 347-87). The historical importance of Roger Bacon's subject is beyond dispute, but the fortuna of his text is not so welldefined as is implied by the introduction in this edition. Similar over-concision becomes even less helpful in the extension of the story to include the work of Johannes Kepler (1571-1630). To summarize: do not let your students read only this book: it partly needs the rest of the good library in which it will be found. All the same, for anyone frivolous or serious enough to plunge straight into the main text, it is very good indeed, with scholarly notes providing hand-holds and water wings.