 The literature on qualia is filled with thought-experiments of one sort or another. Perhaps the most famous of these is the case of Mary, the brilliant color scientist. Mary, so the story goes (Jackson 1982), is imprisoned in a black and white room. Never having been permitted to leave it, she acquires information about the world outside from the black and white books her captors have made available to her, from the black and white television sets attached to external cameras, and from the black and white monitor screens hooked up to banks of computers. As time passes, Mary acquires more and more information about the physical aspects of color and color vision. (For a real life case of a visual scientist (Knut Nordby) who is an achromotope, see Sacks 1996, Chapter 1.) Eventually, Mary becomes the world’s leading authority on these matters. Indeed she comes to know all the physical facts pertinent to everyday colors and color vision. 