In George Orwell's 1984, the main character, Winston Smith, experences a number of conflicts. His main conflicts involve controlling his thoughts and feelings. Smith's world of Oceania is controlled by the Party, which dictates what a person should believe, think, and feel.
Smith, however, has thoughts and feelings that rebel against the Party. He writes in a diary, which is a crime in his society. He has a secret sexual relationship with a woman, Julia, a relationship which goes against Party teachings. Smith eventually confesses his anti-Party sentiments to O'Brien, a confession that eventually leads to Smith being arrested and tortured.
After Smith's arrest, O'Brien has Smith tortured and then re-educated in the thought of the Party. During this process, Smith must learn to control his thoughts. He must learn to think only what the Party wants him to think. Ultimately, Smith will come to the point where he can acknowledge without doubt that "'two and two make five".
Orwell's novel closes with Smith's confession that "He had won the victory over himself. He loved Big Brother." Thus, at least on the surface, the lesson that Smith learns is to gain mastery over his own thoughts and feelings. Indeed, this is a lesson that many people still struggle to learn.