Tomorrow the World!

Can the past affect the future? What if you remembered to the dawn of time when you hated man and decided to destroy him—today!
It was like a cave, a great vaulted cave which echoed back my first hesitant movements on the slab and tossed them from wall to wall until the darkness about me was all one vast rustling. I felt my skin prickle into gooseflesh. In that moment of waking I was oddly frightened. I had no memory of location. I might have been in a subterranean grotto, with enormous stalagmites of supergrotesque shape rising all about me in the thick gloom.
I sat up. The slab was cold beneath me. Directly in front of it towered a thing like a nightmare skeleton of stone.
It was just that: the fossil of a duckbilled dinosaur. I had gone to sleep on a marble bench in the palaeontology room of the museum.
I laughed. The panic that had touched me was gone, and I felt ashamed of myself. Not for falling asleep, because I had been very tired; but ashamed of the fear.
Lord knew how long I had slept. It was black night without and within, and no sound save that of my own movements came to me. The museum must have been closed for hours. The guards had missed me on my bench behind the dinosaur. I stood and shook myself and smoothed the rumpled suit, and began to grope my way between exhibits toward the entrance hall. I left the reptilian skeletons behind—not without a certain relief, for they were awesome sleepers to pass among—and was striding down a dim pathway between glass cases when I heard the footsteps.
A watchman was coming toward me. I could see the reflection of his flashlight. I halted indecisively, growled at myself, and went on. I had a perfectly valid excuse for being there. They could hardly do anything to me.
The guard was big, about my size, and his flash jumped in his hand when he saw me. Then he hurried forward. I grinned into the glare.
Sorry to scare you—
What the hell you doing here, bud?
I did not like him in the least. I fell asleep in the bone room. Just woke up.