Unpublished letters, 'The theory of vision' from W F [William Ford] Stevenson to Samuel Hunter Christie Three letters, dated 1 March 1845, 15 March 1845 and 3 April 1845, in which Stevenson presents a theory on vision. In the first letter, he lays out his theory 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. In the second letter, Stevenson reflects on the doctrine that 'we arrive at a correct vision only by education'. In the third letter, Stevenson asserts his confidence in his theory of vision, and asks Christie to acknowledge receipt of his letters and present them before the Royal Society. Subject: Vision / Optometry Written by Stevenson at Hôtel Meurice, Paris. March-April 1845