For a moment Horning hesitated, then shrugged. "See for yourself." Kneeling, he unsnapped the unit's back plate and exposed the circuits. "The registration dials are set with my own world as zero. You pick up others in the scanning scope as you go, within the limits of the projector drive. After that, it's just a problem of reintegration."
Beside him, the man who was his coexisting self craned. "So that's it! I never dreamed it could be so simple."
"I used a light-loop to help break through the barrier," Horning explained, sketching out a hasty diagram. "It helps to increase the power output--"
"Of course." The other was down on the floor now, probing into the unit's workings. "I've developed all the component elements at one time or another, but when it came to combining them properly, I always managed to miss out."
Horning rose and drained his glass. "Well, you know now," he observed. "For my part, I'm ready to start work on some other project, now that I've gotten to this world."
"I was afraid you'd say that," the other Doctor Raymond X. Horning remarked. Straightening, he snapped shut the back panel of the transdirectional registration unit. "But ... it's not easy."
Horning's counterpart got up. "I mean you can't stay in this world. You're going to have to leave again."
"Yes." Beneath the blandness of the other's manner, a new note rang, grim and unyielding. "As I pointed out, interdimensional transit's a logical impossibility. There's no way of integrating two identical personalities, two selves of the same man, into a highly organized society such as this one."
"And for a reason like that you'd try to force me out--?" Horning took an angry step forward.
But his counterpart jumped back, out of the way. His hand darted to his pocket, whipping out the snub-nosed pistol.
The blandness was gone from the other's face now. The deep-set eyes were cold, the sardonic lines set.
He said: "There's another reason, Doctor. I like my life; I like my wife. And I'm afraid the temptation to relieve me of both might prove too great for you."
"You're being absurd," Horning snapped. "Not to mention insulting."
"Am I?" His counterpart smiled thinly. "I doubt that, my friend. You see, we're one, really. Though we live on separate planes, we both feel the same drives, the same tensions, the same impulses."