This is a mind-bending book that blends excellent history of science with excellent history of art. The core of the book is examination of the origins and early use in visual art of optical perspective, the technique for creating the illusion of three-dimensional space on a two-dimensional plane. The book has a good account of the invention (or at least rediscovery) by the Florentine craftsman and architect Brunelleschi of perspective in 1425, when he created two works (both now lost) that were the first effective, rigorous, and theoretically sound uses of perspective since at least antiquity. The section on Brunelleschi were wonderful, not least because they placed the reader in early-Renaissance Florence. The idea – much less the historical fact – that perspective was invented defies common sense, but Edgerton shows that while everyone does see perspectivally, representing the world in perspective required a genius like Brunelleschi.
Edgerton goes on to describe – with somewhat less surety – Renaissance artists’ use of perspective to make religious art seem more lifelike and therefore more powerful: a good perspectival painting could make the viewer feel that he or she was actually inside the space occupied by, say, the Madonna and Christ Child, or the crucified Christ. Edgerton goes even further than this, linking perspective in art to the development of the “perspective tube” – the device we call the telescope – and to the use of the telescope by Galileo to discover that the moon is actually lumpy, not smooth. Here, Edgerton is on firmer ground again: Galileo was an excellent artist, and was able to determine, based on his views of the moon in 1509, that the patterns of light and dark were actually sunlit and shadowed regions on the moon’s surface – a realization he made because he understood perspectival effects – and because he could render objects – even lunar craters viewed through a telescope – with perspectival techniques.