Sigmund Freud
[Neurologist, psychoanalyst, and thinker, b. 1856, Freiberg, Moravia, Austrian Empire (now Príbor, Czechoslovakia), d. 1939, London, England.]

 We should picture the instrument that carries our mental functioning as resembling a compound microscope or photographic apparatus. 
 [The child receives impressions like] a photographic exposure that can be developed after any interval of time and transformed into a picture.