Read the final paragraph of "How We Entered World War I." In April 1917 the illusion of isolation was destroyed. America came to the end of innocence, and of the exuberant freedom of bachelor independence. That the responsibilities of world power have not made us happier is no surprise. To help ourselves manage them, we have replaced the illusion of isolation with a new illusion of omnipotence. That screen, too, must fall. Which best explains the purpose of repeating the word “illusion” in the paragraph?