 For Boyle, as for other leading seventeenth century figures, perception was a matter of information entering the brain as a result of causal interaction between the perceiver and the perceived object. Arriving at the brain the information was processed by a subsystem or set of subsystems devoted to presenting it to the cognitive system, and to storing it thereafter. The initial processing was done by a system, the common sense, that combined the inputs from the various sense organs (left eye + right eye; eyes + ears; etc.) and it was then imagined — that is, an image was formed in the brain though, as Kepler and Descartes noted explicitly, the image was not a literal, optical, image. That apart, seventeenth century thinkers accepted in general outline the position which had already been set out in the thirteenth century by Roger Bacon, who was in turn simply collating the views of earlier Islamic writers on the subject, though of course the details, particularly the details of the causal interaction between percipient and perceived, varied from writer to writer (See further Lindberg 1976, MacIntosh 1983, and Sutton 1998).