Unpublished letter, 'The theory of vision [part 1]' from W F [William Ford] Stevenson to Samuel Hunter Christie Following a lecture delivered by [Dominique Francois Jean] Arago, Stevenson presents a theory of vision in opposition to the 'present acknowledged theory of vision' which suggests that objects are presented to the mind as they appear to be painted on the retina. He describes an experiment in which one end of a length of polished steel wire is painted red. The wire is presented to the eye in a vertical position with the painted end uppermost. Stevenson states that 'we know that this object will appear to the eye in a position the very reverse of that in which it is painted on the retina; and yet it is quite clear that neither experience nor judgement could have affected a change of position in the mind of the observer'. He goes on to describe another similar experiment, concluding that objects are not presented to the mind as they are found upon the retina, but in the actual position in which are are placed before the spectator. Subject: Vision / Optometry Received 6 March 1845. Written by Stevenson at Hôtel Meurice, Paris. 1 March 1845