"Everybody's happy nowadays" is a hypnopaedic suggestion of Mustapha Mond. What evidence does Huxley offer that this is not true?
The first half of the book describes the mindlessness of work, the replacement of promiscuity for passion, and the use of drugs to stymie personal growth. It sets up the introduction of John Savage into the book. It is through his character that Huxley mainly illustrates that not all of the people are happy about the "brave new world" in which they live. Savage tells Mond that it is his right to be unhappy if he chooses to be, but sadly, he must committ suicide in order to prove it. Most of all, Savage feels the price for living in this society is too great. This is especially shown in the conditioning of babies and children. They're subjected to electric shock to insure their indoctrination against nature works. The adults are given "soma" to numb them to feelings of pain or passion, so books are banned from use since they would stir up these feelings. Again, Savage's character shows us the power of great literature, such as Shakespeare, to stir people's feelings and to elicit emotional responses from the reader.
The themes of the novel are represented by the thoughts, actions, and dialogue of the characters. In this "brave new world", there is no free will and no commitment in relationships. Science and technology are used to restrict the lives of the people, and even "a little knowledge is a dangerous thing".