Some time later his head was working more clearly and he understood that the flow of air implied an exit somewhere. He groped around on the floor until he found one of those elbow-planks, and then crawled sideways, headed upwind. He followed the air for an amount of time impossible to guess at. The low side-tunnel opened out into a smooth-floored space that seemed to be a natural cave. Here the river of air had been broken up into many trickles curving around rocks and stalagmites (tricky to follow), but (nose to floor, tongue out) he followed them for what seemed like a mile, sometimes standing up and walking through spaces that echoed like cathedrals, sometimes squirming on his belly through spaces so close that his head got wedged between the floor and ceiling. He sloshed through a pond of dead water that froze his legs, climbed up the other shore, and entered a mine-tunnel, then passed through tunnels of low and high ceilings, and up-and-down vertical shafts, so many times that he lost track of how many times he had lost track. He wanted badly to sleep, but he knew that if the fire went out while he slumbered, the air-current would stop and he'd lose the thread that, as with that bloke in the myth, was showing him the way out. His eyes, not satisfied with total darkness, fabricated demon-images from all of the bad things he'd seen or thought he'd seen in the last days.