…I am far from holding consciousness to be an “epiphenomenon,” though the doctrine that it is so has aided the development of science. To my apprehension, the function of consciousness is to render self-control possible and efficient. For according to such analysis as I can make the true definition of consciousness is connection with an internal world; and the first impressions of sense are not conscious, but only their modified reproductions in the internal world.
http://www.commens.org/dictionary/entry/quote-pragmatism-24