"How do you control them in the first place?" He sighed. "It isn't really what you would call controls," he said. "It's just the best I can do to keep them from spreading." "But--you said sometimes you separate metals, sometimes you get energy. How do the demons know which you want them to do, if you say you can't control them?" "How do you make an apple tree understand whether you want it to grow Baldwins or Macintoshes?" * * * * * I gawked at him. "Why--but you don't, Greek! I mean it's either one or the other!" "Just so with demons! You're not so stupid after all, are you? It's like improving the breed of dogs. You take a common ancestral mutt, and generations later you can develop an Airedale, a dachshund or a Spitz. How? By selection. My demon entities grow, they split, the new entities adapt themselves to new conditions. There's a process of evolution. I help it along, that's all." He took the little slab of gold from me, brooding. Abruptly he hurled it at the wall. "Gold!" he cried wildly. "But who wants it? I need _help_, Virgie! If gold will buy it from you, I'll pay! But I'm desperate. You'd be desperate too, with nothing ahead but a sordid, demeaning death from young age and a--" I interrupted him. "What's that?" It was a nearby raucous hooting, loud and mournful. Greco stopped in mid-sentence, listening like a hunted creature. "My room," he whispered. "All my equipment--on the floor above--" I stepped back, a little worried. He was a strange man, skinny and tall and wild-eyed. I was glad he was so thin; if he'd been built solidly in proportion to his height, just then he would have worried me, with those staring, frightened eyes and that crazy way of talking. But I didn't have time to worry, in any case. Footsteps were thundering in the halls. Distant voices shouted to each other. The hoot came again. "The fire whistle!" Greco bayed. "The hotel's on fire!" He leaped out of my room into the corridor. I followed. There was a smell of burning--not autumn leaves or paper; it was a chemical-burning smell, a leather-burning smell, a henyard-on-fire smell. It reeked of an assortment of things, gunpowder and charred feathers, the choking soot of burning oil, the crisp tang of a wood fire. It was, I thought for a second, perhaps the typical smell of a hotel on fire, but in that I was wrong. "Demons!" yelled Greco, and a bellhop, hurrying by, paused to look at us queerly. Greco sped for the stairs and up them. I followed. It was Greco's room that was ablaze--he made that clear, trying to get into it. But he couldn't. Black smoke billowed out of it, and orange flame. The night manager's water bucket was going to make no headway against _that_. I retreated. But Greco plunged ahead, his face white and scary. I stopped at the head of the stairs. The flames drove Greco off, but he tried again. They drove him off again, and this time for good.