"Ha, ha, hah! Bravo, Sarsem!"

"Thereupon, your representative—"

"Speak less loosely, Sarsem. The person was not my representative."

' 'While this person was temporarily distracted, I laid the old prism safely aside. This person, whose good faith you decry, still cannot be deemed irresponsible."

"Why do you say that?"

"Because, like myself, he worried about the safety of the old Perciplex and would not rest until he learned where I had placed it."

Rhialto groaned. "Within the confines of a cavern?"

"Yes; how did you know?"

"We are not without resources. In effect you yielded up the Perciplex to the criminal!"

"Not at all. I placed the prism in a place well-known to me, accessible only by a small and narrow fissure. For double security I reverted the object to the 16th Aeon." "And how do you know that the criminal himself has not reverted to this era and taken the Perciplex for his own?''

"Can he walk the length of a fissure into which you cannot even thrust your hand? Especially while I keep the opening under survey from then till now, as you might scan the surface of the table? Nothing has come or gone. Ergo, by the rotes of rationality, the Perciplex reposes in its subterranean place, as secure as ever."

Rhialto rose to his feet. "Come once more back to Fader's Waft! You shall grope down the fissure into the 16th Aeon and reclaim the Perciplex. Ildefonse, are you ready? Summon your small air-carriage."

9

Rhialto, Ildefonse and Sarsem stood disconsolate on the summit of Fader's Waft. Sarsem spoke in a troubled voice. "A most confusing dilemma! I searched the fissure without success; I guarantee that the Perciplex did not leave by this route. I admit to perplexity."

Rhialto suggested: "There may be another route into the cavern; what of that?"

"The idea is plausible," admitted Sarsem. "I will make a survey across the Aeons."

Sarsem presently returned to make his report. "The cave opened to the valley for a brief period during the 16th Aeon. The entrance is not evident now. This is good news, since if I am a trifle nonplussed, our antagonist must be crazy with bafflement."

"Not necessarily true," intoned Rhialto.

Sarsem peered here and there. "In the 16th Aeon, so I recall, three black crags rose yonder, and a river swung into the valley from the east. . . Fader's Waft at that time was a tall peak defying the storms. . . . Now I am straight. We must drop down into yonder valley."

Sarsem led the way down a barren slope into a gulch choked with tumbled stones.

"Much has changed," said Sarsem. "A crag the shape of a skatler horn rose yonder and another there, and another there, where you now see rounded hummocks. Perhaps among these rocks. . . . Here is the place, though the entrance is tumbled over with detritus. Stand aside; I will skew the latifers, so as to allow access."

Sarsem caused a pulse to shiver along the hillside, whisking away the overburden and revealing an aperture leading into the mountain.