"The Butter Battle Book," which was published in 1984, may have been Geisel's most controversial work. The story revolves around two mutually antagonistic cultures called the Yooks and the Zooks, a veiled reference to the United States and Soviet Union. Both sides are divided on what should be the trivial issue of whether bread should be buttered on the top or bottom of the slice. The divide leads to an arms race and the book ends with both sides facing off against one another on top of a wall, an allusion to the wall in Berlin. The final page is blank, inviting readers to finish the story themselves.
The story tackles the heavy issue of nuclear annihilation and mutually assured destruction. Despite the subject matter, the book was popular primarily among adults and held a place on the New York Times' best-seller list for six months, according to BBC News.
Libraries across the country yanked the book, partly because of the downbeat ending that could frighten younger children, but also because of the story's political messaging.
A less controversial, though no less serious work, is "Yertle the Turtle," a book whose title masks the message hidden within. Yertle, a turtle who's king of the pond, insists that his followers stack one on top of the other as high as the moon so that he can have a taller throne. Yertle is so obsessed with being above everyone and everything else that he even gets upset when the moon rises above him. His endless ambition ultimately proves his downfall as a simple turtle burp leads to Yertle's literal fall from grace.
Published in 1958, the book is an allegory of the ruthless pursuit of ambition by dictators. Specifically, Geisel designed the character of Yertle after Adolf Hitler. Geisel's message is that all dictators eventually meet the same fate and the people (or turtles) who were once oppressed will win back their freedom.