Having picked out again the hallway through which I had come, I started to return to the structure’s entrance. Additional exploration could wait for another day. Groping a course as best I could through the spiral corridor — with only general sense, memory, and a vague recognition of some of the ill-defined weed patches on the plain as guides — I soon found myself once more in close proximity to the corpse. There were now one or two farnoth-flies swooping over the helmet-covered face, and I knew that decay was setting in. With a futile instinctive loathing I raised my hand to brush away this vanguard of the scavengers — when a strange and astonishing thing became manifest. An invisible wall, checking the sweep of my arm, told me that — notwithstanding my careful retracing of the way — I had not indeed returned to the corridor in which the body lay. Instead, I was in a parallel hallway, having no doubt taken some wrong turn or fork among the intricate passages behind.
Hoping to find a doorway to the exit hall ahead, I continued my advance, but presently came to a blank wall. I would, then, have to return to the central chamber and steer my course anew. Exactly where I had made my mistake I could not tell. I glanced at the ground to see if by any miracle guiding footprints had remained, but at once realised that the thin mud held impressions only for a very few moments. There was little difficulty in finding my way to the centre again, and once there I carefully reflected on the proper outward course. I had kept too far to the right before. This time I must take a more leftward fork somewhere — just where, I could decide as I went.
As I groped ahead a second time I felt quite confident of my correctness, and diverged to the left at a junction I was sure I remembered. The spiralling continued, and I was careful not to stray into any intersecting passages. Soon, however, I saw to my disgust that I was passing the body at a considerable distance; this passage evidently reached the outer wall at a point much beyond it. In the hope that another exit might exist in the half of the wall I had not yet explored, I pressed forward for several paces, but eventually came once more to a solid barrier. Clearly, the plan of the building was even more complicated than I had thought.
I now debated whether to return to the centre again or whether to try some of the lateral corridors extending toward the body. If I chose this second alternative, I would run the risk of breaking my mental pattern of where I was; hence I had better not attempt it unless I could think of some way of leaving a visible trail behind me. Just how to leave a trail would be quite a problem, and I ransacked my mind for a solution. There seemed to be nothing about my person which could leave a mark on anything, nor any material which I could scatter — or minutely subdivide and scatter.
My pen had no effect on the invisible wall, and I could not lay a trail of my precious food tablets. Even had I been willing to spare the latter, there would not have been even nearly enough — besides which the small pellets would have instantly sunk from sight in the thin mud. I searched my pockets for an old-fashioned notebook — often used unofficially on Venus despite the quick rotting-rate of paper in the planet’s atmosphere — whose pages I could tear up and scatter, but could find none. It was obviously impossible to tear the tough, thin metal of this revolving decay-proof record scroll, nor did my clothing offer any possibilities. In Venus’s peculiar atmosphere I could not safely spare my stout leather suit, and underwear had been eliminated because of the climate.
I tried to smear mud on the smooth, invisible walls after squeezing it as dry as possible, but found that it slipped from sight as quickly as did the height-testing handfuls I had previously thrown. Finally I drew out my knife and attempted to scratch a line on the glassy, phantom surface — something I could recognise with my hand, even though I would not have the advantage of seeing it from afar. It was useless, however, for the blade made not the slightest impression on the baffling, unknown material.
Frustrated in all attempts to blaze a trail, I again sought the round central chamber through memory. It seemed easier to get back to this room than to steer a definite, predetermined course away from it, and I had little difficulty in finding it anew. This time I listed on my record scroll every turn I made — drawing a crude hypothetical diagram of my route, and marking all diverging corridors. It was, of course, maddeningly slow work when everything had to be determined by touch, and the possibilities of error were infinite; but I believed it would pay in the long run.
The long twilight of Venus was thick when I reached the central room, but I still had hopes of gaining the outside before dark. Comparing my fresh diagram with previous recollections, I believed I had located my original mistake, so once more set out confidently along the invisible hallways. I veered further to the left than during my previous attempts, and tried to keep track of my turnings on the record scroll in case I was still mistaken. In the gathering dusk I could see the dim line of the corpse, now the centre of a loathsome cloud of farnoth-flies. Before long, no doubt, the mud-dwelling sificlighs would be oozing in from the plain to complete the ghastly work. Approaching the body with some reluctance, I was preparing to step past it when a sudden collision with a wall told me I was again astray.