"But our work is most important, Mr. Malone," Dr. O'Connor said with a motion of his eyebrows. "As I'm sure you must understand."
"Oh," Malone said, feeling if he'd been caught without his homework, "of course. But if you don't mind—"
"Yes, Mr. Malone?" Dr. O'Connor said smoothly.
"What I want to know," Malone said, "is this. What are the limitations of this—uh—phenomenon?"
Dr. O'Connor brightened up thoroughly. "Well, theoretically," he said, "there do not appear to be any limitations. However, practical limitations do exist. If the process is at all parallel with psychokinesis, or with levitation"—he stared at Malone, as if daring him to say that it wasn't—"if that parallel exists, then the subject is mentally limited by his own physical strength."
Malone said, "What?"
"Try and be patient, Mr. Malone," O'Connor said calmly. "Please. As I was saying, the subject is limited by his own physical strength. In other words, he cannot move psionically any subject larger than he can lift physically. This appears to be a psychological limitation which—"
"Oh," Malone said. "You mean he couldn't carry off a building, or anything like that?"
"Of course not," Dr. O'Connor said. "Nor, as a matter of fact, could he carry off anything that was securely bolted down. I hope you follow me."
"I think so," Malone said. "But look here. Suppose you handcuffed him to, say, a radiator, or a jail cell bar."