Dark Reality

Out of a future too dimly discerned to be comprehensible one was chosen. Why—no one knew or could know.
Slowly, wearily, the yellow sun went down the sky. From the east the night came on, as dark and as deep as the night that has no ending.
The last rays of the sun washed down over the planet, over the low rounded hills and the trees that grew on them, through the shallow valleys where the grass grew rank and luxurious. The last songs of the birds came undisturbed through the dusk. A deer snorted. From somewhere came the bark of another animal, a bark that ended in a howl, long-drawn and mournful.
Dawn world or dusk world?
The night flowed into the valleys, filled them with a mystic darkness. The darkness crept to the tops of the low hills. Slowly it crept around a huge ball that rested on top of the nearer hill. The ball, perhaps fifty feet in diameter, lifted a foot from the ground. It quivered, lifted two feet, then slowly settled back to earth.
The darkness came in around it, touched it, hid it from sight.
Lee Garth twisted in his chair. Wearily he laid the pencil down. The equations wouldn't work right. They kept trying to run off into impossible combinations. There was an erratic but persistent gadfly of thought buzzing in his mind, a vague shadowy movement in his brain. Like a ghost from shadow-land it twisted through his brain, twisting through the dark convolutions where his memory lay testing the open synapses, seeking a place where a short circuit would result in action.
Fretfully, Lee Garth picked up the pencil. But there was a thinking in his mind, a formless thinking that was somehow purposeful. He sensed the import of that purpose. Tiny chills ran over his body, tiny rivers of icy cold. His fingers trembled. The pencil moved over the page. Garth was first puzzled, then perturbed, then lost in a vast unease.
Here and there upon this earth are fields where men, looking backward, see how the stream of history shifted.