Of course I did not say all this to the old woman. From experience I know that the most torturing thing is to inoculate someone with a doubt as to the fact that he or she is a three-dimensional reality and not some other reality. I remarked only, quite drily, that her business was to open the gate, and she let me into the courtyard. It was empty. Quiet. The wind remained beyond the walls, distant as on that day, when shoulder to shoulder, two like one, we came out from beneath, from the corridors,--if it ever really happened. I walked under stone arches, my steps resounded against the damp vaults and fell behind me, sounding as though someone were continually following me. The yellow walls with patches of red brick were watching me through their square spectacles, windows,--watching me open the squeaky doors of a barn, look into corners, nooks and hidden places.... A gate in the fence and a lonely spot. The monument of the Two Hundred Years' War. From the ground naked, stone ribs were sticking out. The yellow jaws of the wall. An ancient oven with a chimney like a ship petrified forever among red-brick waves. It seemed to me that I had seen those yellow teeth once before. I saw them still dimly in my mind, as at the bottom of a barrel, through water. And I began to search. I fell into caves occasionally; I stumbled over stones; rusty jaws caught my unif a few times; salt drops of sweat ran from my forehead into my eyes. Nowhere! I could find that exit from below, from the corridors, nowhere! There was none. Well, perhaps it was better that it happened so. Probably that _all_ was only one of my absurd "dreams." Tired out, covered with cobweb and dust, I opened the gate to return to the main yard, when suddenly ... a rustle behind me, splashing steps, and there before me were the pink wing-like ears and the double-curved smile of S-. Half closing his eyes, he bored his little drills into me and asked: "Taking a walk?" I was silent. My arms were heavy. "Well, do you feel better now?" "Yes, thank you. I think I am getting normal again." He let me go. He lifted his eyes, looked upward, and I noticed his Adam's apple for the first time; it resembles a broken spring, sticking out from beneath the upholstery of a divan. Above us, not very high (about 50 meters) aeros were buzzing. By their low, slow flight and by the observation tubes which hung down, I recognized them. They were the aeros of the Guardians. But there were not two or three, as usual, there were about ten or twelve (I regret to have to confine myself to an approximate figure). "Why are there so many today?" I dared to ask S-. "Why? Hm.... A real physician begins to treat a patient when he is still well but on the way to becoming sick tomorrow, day-after-tomorrow or within a week. Prophylaxis! Yes!" He nodded and went splashing over the stones of the yard. Then he turned his head and said over his shoulder, "Be careful!"