A very faint smile seemed to tug at the corners of the thin Vulcan lips. "I might have underestimated you, Doctor," the captain replied. But any amusement he may have felt quickly faded. "There is only one additional question I must put to you before proceeding further."

McCoy waited.

"Do you have a theory as to why only certain individuals appear to be affected by the madness?" the Vulcan asked presently.

"As a matter of fact," McCoy said with a grin, "I do. If—and I repeat ifthis dual universe theory is correct—then it stands to reason that a few things are always going to be the same." He shrugged. "Like with the Halkans, for instance: same people in both universes, same basic life-roles; just a different dimensional plane.

"But I'm starting to think that those people who aren'taffected are playing the same role in thisuniverse that they play in … in whatever universe they really belong to." He shook his head. "Hell, Spock, I'm a doctor, not a theoretical scientist, but I think you catch the general drift. Just using myself as an example, I'm probably not being affected because I'm a doctor in both places. Reichert, on the other hand …" He paused for a moment. "Reichert has the mental composition in thisuniverse which made him an engineer's mate. But in anotheruniverse—the ' real' universe, if you will—he could well be a businessman or a merchant, or even a pimp on Rigel! Who knows? But he's probably something completely different." He hesitated once again. "And yet," he continued at last, "the very molecules which determine how a mind operates are preset in the genetic code of the parents. And if that coderemains the same in two different universes—yet the environmentalters in the parallel universe, then it throws the brain out of kilter. The results: eventual insanity due to an inability to cope with change." He shrugged once more. "Or if you want to get downright psychiatric about it, it's the square peg and round hole theory: the mind rebels against anything which is essentially contrary to personal nature."

After a moment of silence, the Vulcan opened the top drawer of the desk, withdrawing a second computer tape. "In essence," he stated, "your theories confirm my own—and the theories of the ship's central research computers as well." He paused. "I have also taken the liberty of plotting a time curve—which, I believe, will tell us precisely how long we have before the condition worsens beyond the point of repair."

McCoy's eyes widened as the Vulcan's words sank in. He stared blankly at the tape. "Why didn't you tell me this an hour ago, Spock?" he demanded, wondering if the Vulcan had merely wanted to see him squirm.

The captain rose, pacing the width of the quarters. And when he spoke again, his voice was very quiet, almost strained. "Since I myself am being … affected … by this apparent alteration, I did not feel I could trust my own theories exclusive of all others. I … wished to see if you and I, operating under different conditions, would reach the same conclusion and form the same hypotheses independently of one another."

McCoy felt himself soften toward the captain. It wasn't often that Spock admitted to anydoubts, any weaknesses. "Then … I take it you've had … more problems?"

The Vulcan's eyes closed—almost painfully. "According to my calculations, Doctor," he replied, evading the direct question, "we have precisely fifteen Vulcan Standard Days before the insanity spreads beyond any chance of controlling or isolating its effects." He indicated the tape with a quick nod of his head. "During that time, we must endeavor to …"

"To what?" McCoy demanded, a moment of hopelessness creeping in to join with frustration. "Build a universe that none of us can even prove exists? And in fifteen days?" he laughed disbelievingly. "Hell, Spock, legend has it that the Earth was created in seven days! And now you're telling me that you and I—a Vulcan and a mere mortal—are going to construct an entire universe in two weeks!" Again came the sarcastic laugh. "No problem, Spock," he said reassuringly. "You handle the nebulaes and the quasars; I'll take care of the little things: like planets, suns, and weird personality quirks of trillions of lifeforms!"

The Vulcan lifted one admonishing brow. "If you can suggest some alternative, Doctor, I would be more than willing to entertain the idea."

McCoy rose from the chair, started to speak, then settled for bouncing up and down on his toes as his lips tightened.

"If not," the Vulcan continued, "then I suggest you review the prepared tape at once. You will find computer confirmation of your theories in the recording, Doctor."

McCoy bit his lower lip in frustration, hard-pressed to ignore the icy Vulcan tone. "Right," he said at last, forcing calm on himself. "And I suggest you do the same with the vid-scan tape, Spock." He turned to leave, then abruptly changed his mind. "Oh—you'll notice that 13 out of the 198 tapes we ran show a negative scan under coenthal."

An eyebrow rose. "Explanation?"

McCoy felt Death peer over his shoulder. "It's purely speculation, of course, but … my personal theory is that those thirteen people have … already lived out their lives in whatever other universe there may be." He paused, thinking about that. "Which raises the question of morality—do we have the right to … sentence those people to death—when they've essentially been given another chance at life?"

For a long time, the Vulcan was silent. "Perhaps a more appropriate question would be: Do we have the right notto, considering all that is at stake?"

McCoy took a deep breath. "Either way, Spock, it's bartering lives." But he waved the argument aside, forcing himself to understand the Vulcan's situation; he was just relieved to be in his own shoes and not the captain's. "I know there's no easy answer," he said softly, "so don't feel compelled to find one. It's just one more angle to be considered."

The Vulcan's head inclined in acknowledgment as he glanced nervously at the desk chronometer. "I see," he murmured, returning to the chair and sitting down. He looked up, meeting McCoy's eyes. "Was there anything else, Doctor?"

McCoy shook his head. "Oh, yes," he suddenly remembered. "There isone other thing." He sat down once again. "That new ensign—Kirk?"

The Vulcan glanced sharply at the doctor.

"Well," McCoy drawled, grateful for the change of subject, "I talked to his new roommate yesterday afternoon—Jerry Richardson—and he said that he hasn't seen hide nor hair of Kirk since you had the quartermaster move the two of them in together." McCoy shrugged. "Maybe nothing," he said before the Vulcan could respond. "But once you take a look at those vid-scans, I think you'll understand why I'm a little … concerned about Kirk."

"Please explain," the Vulcan entreated, leaning forward curiously.

"I can't be sure, of course," the doctor replied hesitantly, "but Kirk doesbear a remarkable resemblance to some of the images on that tape." He leaned back, biting his lip thoughtfully. "And I also found out that you ordered Kirk to report to Sickbay last night."

"He did not choose to do so," the Vulcan stated, not particularly surprised.

"Apparently not," McCoy confirmed. "But if you questioned him about it, he'd probably give you a lot of static about his ignoring an order being grounds for immediate discharge, and you wouldn't get much insight into the real problem." He paused. "But Kirk didcome staggering into my office early this morning. And let me tell you, Captain, he looked like early death and plomik soup warmed over. At first, he wouldn't tell me what was wrong, wouldn't let anyone touch him—but then he started demanding lidacin."