Below lay the tomb world, the immutable cause-and-effect world of the demonic. At median extended the layer of the human, but at any instant a man could plunge—descend as if sinking—into the hell-layer beneath. Or: he could ascend to the ethereal world above, which constituted the third of the trinary layers. Always, in his middle level of the human, a man risked the sinking. And yet the possibility of ascent lay before him

Philip K Dick, The Three Stigmata of Palmer Eldritch [Amazon, Bookshop, Publisher, Local Library]