In that great social organ which, collectively, we call literature, there may be distinguished two separate offices, that may blend and often do so, but capable, severally, of a severe insulation, and naturally fitted for reciprocal repulsion. There is, first, the literature of knowledge, and, secondly, the literature of power. The function of the first is to teach; the function of the second is to move: the first is a rudder; the second an oar or a sail.