it may be a labyrinth, but can also be a gold-mine—his ideas themselves eventually acquire a twilight-colour of their own, and an odour, as much of the depth as of the mould, something uncommunicative and repulsive, which blows chilly upon every passer-by. The recluse does not believe that a philosopher—supposing that a philosopher has always in the first place been a recluse—ever expressed his actual and ultimate opinions in books: are not books written precisely to hide what is in us?—indeed, he will doubt whether a philosopher CAN have "ultimate and actual" opinions at all; whether behind every cave in him there is not, and must necessarily be, a still deeper cave: an ampler, stranger, richer world beyond the surface, an abyss behind every bottom, beneath every "foundation."