We do not see things the way they are, but as we are.
Jewish Proverb (The Talmud) and/or Anais Nin
Walter Sickert told his pupils that they could not draw the human hand because they thought of it as a hand. And because they thought of it as a hand, they thought they already knew what it ought to be. Thus they did not look at the hand in front of their eyes, but at the hand in back of their eyes.
T. E. Hulme, Speculations