I took three of the stronger pills that night, turned off the light and lay back in bed, waiting for sleep to come and get me. The antiseptic odor of the Medical Center recalled itself, but nothing else happened, and I was still waiting to go to sleep when I woke up next morning. No dreams of a breakfast I couldn't eat, no dreams at all. I had been smelling the memory of formaldehyde and just slid off to sleep. I could still smell it, for that matter, as if it were coming from the slightly open bedroom window. I looked up. "Hallo," said the tall skinny man in a doctor's coat on the window sill. "Hallo yourself," I said. "Go away, I'm awake." "Yes, you are. At least I assume you are. But I'm not." I sat up and looked at him, and he obligingly turned his head to profile against the brightness of the window. He had a sharp, beaky face that was familiar. "Haven't we met somewhere?" I asked. "Certainly," he said, in a slightly affected voice. "Well?" "I don't know your name," he said, "but I have a very important post-operative case at present, and you keep charging around the ward when you're asleep. I just came over, as soon as I could get a few hours' sleep myself, to ask you to stop doing it, if you don't mind." "I've done no such thing." "You were doing it all last night, my friend." "I was not," I said. "I spent last night here in my own bed. I didn't even dream." "Ah, that probably accounts for it. Tell me, do you take drugs, tranquilizers, by any chance? We've had a lot of trouble with that. They seem to cause a bubble in the sequence of probabilities and things shift about. I've been taking a new one myself, while this case is on. I suspect that although I'm dreaming you, I think, you are not asleep at all. At least I wasn't when you made all that noise in my ward last night." "No, I'm awake," I said. "Very much so." "I see. Well, I shall wake up soon myself and go back to my own world, of course. But while I'm here, I suppose you haven't any advanced works on post-operative hyperspace relapse? "Pity," he said, as I shook my head. "I suppose you have no information on the fourth octave of ultra-uranium elements?" He shook his head. "Didn't even know they existed," he said. "I don't believe they do in my probable time. What are you, a physicist? Ah," he added, as I nodded, "I wanted to specialize in physics when I was in college, but I went in for medicine instead." "So did I," I said, "medicine, I mean, but I never passed pharmacology with all those confusing extraterrestrial derivatives." "Really?" he said interestedly. "It's my weakest subject, too. I'm a pretty good surgeon, but an awful fool with medications. I suppose that's how we got together. You won't come busting up the ward again, will you?" "I'd like to be obliging, but if I don't dream and I don't know where I am when I'm asleep, I don't see what I can do to stop it. It's not as if I'm really there, is it?" * * * * *