All images are abstractions.

Found this in Kit White's "101 things to Learn in Art School" (The MIT Press, 2011) as lesson #14:
"All images are abstractions.
Even photographs. They are never the thing pictured; they are a conceptual or mechanical reproduction of a thing past. This may seem obvious, but it has everything to do with the way we perceive and use images. As pictures are symbolic assemblages of forms, recognizable or not, they are always metaphors. Metaphor is the medium of symbolic language and is the language of art. Realism in art is anything but. The greater the art, the greater the illusion."
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Kit White accompanied this by an own image after Rene Magritte, a creator of great illusions and metaphors.