In America, we love a rags-to-riches tale. Think of Andrew Carnegie, the Scottish immigrant who rose from bobbin boy to steel magnate; Oprah Winfrey, who grew up poor in rural Mississippi; even Elon Musk, the awkward South African transplant who transformed himself into the richest man alive.

"The future is certain," the Soviet joke goes. "It's the past that keeps changing." This wisecrack and its variants hit at one of communism's central absurdities: The doctrinaire Marxists believed they had the key to understanding all of human affairs, but they constantly had to conceal their many mistakes.

If your child attends elementary school in the United States, there is a good chance that the school uses an online reading tool called Epic.