The mind's magic lantern: David Brewster and the scientific imagination

The imagination has always been thought to operate primarily in conjunction with the sense of vision, imagined objects and scenes being conjured up before the ‘mind’s eye’. In early nineteenth-century Scotland the natural philosopher David Brewster developed a theory of the imagination that explained its operation through a reversal of the normal processes of visual perception. These ideas were rooted in the mental philosophy of the eighteenth-century Scottish Enlightenment. For Brewster the mind’s eye was also the eye of the body, and images from the memory and imagination were projected onto the retina in the same manner that images were projected onto the screen in a magic lantern show. This theory underpinned his belief that imagination played an essential role in scientific discovery. Brewster believed that this process was as essential to the discoveries of science as it was to the creation of great poetry. The writings of Brewster can tell us a great deal about the connections between science and literature in the early nineteenth century, as well as showing that the philosophy of science in contemporary Britain was far from monolithic.