1933, Germans burnt thousands of books. The Nazi Party had just been voted as largest party into the German parliament and took every effort to spread their ideology among the masses. Now, ideology is nothing you can just spray on people, they need to take it onto themselves. So the Nazis created a marketing campaign which in their dictatorship turned into a well-oiled propaganda machine.
One of the early actions was the book burnings. There to show power, strength and control over the self-proclaimed enemies of the "pure" germaneness: Jews, "leftists", artists, free thinking people.