INSTANT OF DECISION BY RANDALL GARRETT - https://www.gutenberg.org/cache/epub/32088/pg32088-images.html

 How could a man tell the difference if all the reality of Earth turned out to be a cosmic hoax? Suppose it turned out that this was just a stage set for students of history?

Even after the collapse of Communism after the war, the world hadn't learned anything, it seemed. The Eurasian League had seemed, at first, to be patterned after the Western world's United Nations, but it hadn't worked out that way.