Extramission Quotes

There were many natural philosophers, particularly in the West, who looked to al-Kindi for support in their defense of a combined intromission-extramission theory. Grosseteste, an early defender of such a combined theory, was in all likelihood familiar with al-Kindi's De aspectibus and probably had al-Kindi in mind when he wrote: "However, mathematicians and physicists, whose concerns is with those things that are above nature, ...maintain that vision is produced by extramission." Later in the thirteenth century Roger Bacon and John Pecham also appealed to the authority of al-Kindi to support their contention that rays issue from, as well as enter, the observer's eye. (John Peckham)