Explore "Invaders from the Infinite" by John W. Campbell on Textopian. Read with annotations and highlights.
They were getting very near their own time, Arcot felt. Indeed, they must already exist on Earth. "One thing that puzzles me," he commented, "is what would happen if we were to go down now, and see ourselves."
"Either we can't or we don't want to do it," pointed out Morey, "because we didn't."