[47] It is from this confused assumption that the time-honored riddle comes, of how, with an upside-down picture on the retina, we can see things right-side up. Our consciousness is _naïvely_ supposed to inhabit the picture and to feel the picture's position as related to other objects of space. But the truth is that the picture is non-existent either as a habitat or as anything else, for immediate consciousness. Our notion of it is an enormously late conception. The outer object is given immediately with all those qualities which later are named and determined in relation to other sensations. The 'bottom' of this object is where we see what by touch we afterwards know as our _feet_, the 'top' is the place in which we see what we know as other people's heads, etc., etc. Berkeley long ago made this matter perfectly clear (see his Essay towards a new Theory of Vision, §§ 93-98, 113-118). [48] For full justification the reader must see the next chapter. He may object, against the summary account given now, that in a babe's immediate field of vision the various things which appear are located _relatively to each other_ from the outset. I admit that _if discriminated_, they would appear so located. But they are parts of the content of one sensation, not sensations separately experienced, such as the text is concerned with. The fully developed 'world,' in which all our sensations ultimately find location, is nothing but an imaginary object framed after the pattern of the field of vision, by the addition and continuation of one sensation upon another in an orderly and systematic way. In corroboration of my text I must refer to pp. 57-60 of Riehl's book quoted above on page 32, and to Uphues: Wahrnehmung und Empfindung (1888), especially the _Einleitung_ and pp. 51-61. CHAPTER XVIII. IMAGINATION. _Sensations, once experienced, modify the nervous organism, so that copies of them arise again in the mind after the original outward stimulus is gone._ No mental copy, however, can arise in the mind, of any kind of sensation which has never been directly excited from without. The blind may dream of sights, the deaf of sounds, for years after they have lost their vision or hearing;[49] but the man _born_ deaf can never be made to imagine what sound is like, nor can the man _born_ blind ever have a mental vision. In Locke's words, already quoted, "the mind can frame unto itself no one new simple idea." The originals of them all must have been given from without. Fantasy, or Imagination, are the names given to the faculty of reproducing copies of originals once felt. The imagination is called 'reproductive' when the copies are literal; 'productive' when elements from different originals are recombined so as to make new wholes.