"An ancient principle specifies that, in order to destroy a substance, the nature of the substance must be determined. In short, before Blikdak may be dissolved, we must discover his elemental nature." And his eyes moved glassily to Guyal.

"Your pronouncement is sound beyond argument," admitted Guyal, but how may this be accomplished? Blikdak will never allow such an investigation."

"No; there must be subterfuge, some instrumentality . . ."

"The ghost are part of Blikdak's stuff?".

"Indeed."

"Can the ghosts be stayed and prevented?"

"Indeed; in a box of light, the which I can effect by a thought. Yes, a ghost we must have." Kerlin raised his head. "Baton! one ghost; admit a ghost!"

A moment passed; Kerlin held up his hand. There was a faint scratch at the door, and a soft whine could be heard without. "Open," said a voice, full of sobs and catches and quavers. "Open and let forth the youthful creatures to Blikdak. He finds boredom and lassitude in his vigil; so let the two come forth to negate his unease."

Kerlin laboriously rose to his feet. "It is done."

From behind the door came a sad voice, "I am pent, I am snared in scorching brilliance!"

"Now we discover," said Guyal. "What dissolves the ghost dissolves Blikdak."

"True indeed," assented Kerlin.

"Why not light?" inquired Shierl. "Light parts the fabric of the ghosts like a gust of wind tatters the fog."

"But merely for their fragility; Blikdak is harsh and solid, and can withstand the fiercest radiance safe in his demon-land alcove." And Kerlin mused. After a moment he gestured to the door. "We go to the image-expander; there we will explode the ghost to macroid dimension; so shall we find his basis. Guyal of Sfere, you must support my frailness; in truth my limbs are weak as wax."

On Guyal's arm he tottered forward, and with Shierl close at their heels they gained the gallery. Here the ghost wept in its cage of light, and searched constantly for a dark aperture to seep his essence through.

Paying him no heed Kerlin hobbled and limped across the gallery. In their wake followed the box of light and perforce the ghost.

"Open the great door," cried Kerlin in a voice beset with cracking and hoarseness. "The great door into the Cognative Repository!"

Shierl ran ahead and thrust her force against the door; it slid aside, and they looked into the great dark hall, and the golden light from the gallery dwindled into the shadows and was lost.

"Call for Lumen," Kerlin said.

"Lumen!" cried Guyal. "Lumen, attend!"

Light came to the great hall, and it proved so tall that the pilasters along the wall dwindled to threads, and so long and wide that a man might be winded to fatigue in running a dimension. Spaced in equal rows were the black cases with the copper bosses that Guyal and Shierl had noted on their entry. And above each hung five similar cases, precisely fixed, floating without support.