Burgess was a closet homosexual. The book in question is supposed to make people look at the society they live in, and imagine the roles had been reversed, straight people being persecuted instead of gay people. Which is done in an attempt to get people to empathise more with gay people.The book even has society transitioning from vilifying heterosexual trends to glorifying free love and orgies, which is a mirror image of what some people believe will happen if gay people are accepted. The other themes are government brainwashing, population control and human nature.