Itz didn't seem to care. She marched around my head and back again, now and then laid a tentative paw on my nose or chin, and kept up a steady rumbling purr. The feeling of affection I had for that cat right then was close to being one of my life's grand passions. My hands roamed over her scrawny frame, fingered again the khaffite collar I had whiled away an hour in fashioning for her aboard the lifeboat-- My head hit the stone wall with a crack I didn't even notice. In ten seconds I had released the collar clasp, pulled the collar from Itzenca's neck, thumbed the stiff khaffite out into a blade about ten inches long, and was scraping at the mortar beyond my head at fever heat. * * * * * They had fed me three times by the time the groove was nine inches deep on all sides of the block; and the mortar had hardened. But I was nearly through, I figured. I took a rest, then made another try at loosening the block. I thrust the blade into the slot, levered gently at the stone. If it was only supported on one edge now, as it would be if it were a little less than a foot thick, it should be about ready to go. I couldn't tell. I put down my scraper, got into position, and pushed. I wasn't as strong as I had been; there wasn't much force in the push. Again I rested and again I tried. Maybe there was only a thin crust of mortar still holding; maybe one more ounce of pressure would do it. I took a deep breath, strained ... and felt the block shift minutely. Now! I heaved again, teeth gritted, drew back my feet, and thrust hard. The stone slid out with a grating sound, dropped half an inch. I paused to listen: all quiet. I shoved again, and the stone dropped with a heavy thud to the floor outside. With no loss of time I pushed through behind it, felt a breath of cooler air, got my shoulders free, pulled my legs through ... and stood, for the first time in how many days.... I had already figured my next move. As soon as Itzenca had stepped out I reached back in, groped for the water bottle, the dry crusts I had been saving, and the wad of bread paste I had made up. I reached a second time for a handful of the powdered mortar I had produced, then lifted the stone. I settled it in place, using the hard bread as supports, then packed the open joint with gummy bread. I dusted it over with dry mortar, then carefully swept up the debris--as well as I could in the total darkness. The bread-and-water man would have a light and he was due in half an hour or so--as closely as I had been able to estimate the time of his regular round. I didn't want him to see anything out of the ordinary. I was counting on finding Foster filed away somewhere in the stacks, and I'd need time to try to release him.