She shook her head. "No," she said. "No, it's not any good to ask. I have no right to ask. I'll simply have to tell' you and trust to your discretion. And I'm pretty sure it's true. Time has been made an offer for the Artifact."

Silence reverberated in the room as the other three sat motionless, scarcely breathing. She looked from one to the other of them, not quite understanding.

Finally Ghost stirred slightly and there was a rustling in the silence of the room, as if his white sheet had been an actual sheet that rustled when he moved.

"You do not comprehend," he said, "the attachment that we three hold to the Artifact."

"You struck us in a heap," said Oop.

"The Artifact," said Maxwell softly. "The Artifact, the one great mystery, the one thing in the world that has baffled everyone..."

"A funny stone," said Oop:

"Not a stone," said Ghost.

"Then, perhaps," said Carol, "you'll tell me what it is."

And that was the one thing, Maxwell told himself, that neither Ghost nor any one else could do. Discovered ten years or so ago by Time investigators on a hilltop in the Jurassic Age, it had been brought back to the present at a great expenditure of funds and ingenuity. Its weight had demanded energy far beyond anything so far encountered to kick it forward into time, an energy requirement which had made necessary the projection backward into time of a portable nuclear generator, transported in many pieces and assembled on the site. And then the further task of bringing back the generator, since nothing of that sort, as a matter of simple ethics, could be abandoned in the past- even in the past of the far Jurassic.

"I cannot tell you," said Ghost. "There is no one who can tell you."

Ghost was right.