Most of Winston's thoughts are thoughtcrimes. His entire relationship with Julia is a crime because he is indulging in a relationship that is not in keeping with the state's idea of the purpose of sex and indulging in the crime of having his "ownlife." Orwell makes it clear when he tells us that "Their embrace had been a battle, the climax a victory. It was a blow struck against the Party. It was a political act." Winston also insists that 2 + 2 = 4. He claims that no matter what the party says, this will always be true; believing that there is a truth outside the party is an example of thought crime. Collecting the little shell from Charrington is another thought crime because it values something from the past. And his biggest thoughtcrime is obtaining a copy of and reading the test of "The Theory of Oligarcic Collectivism." This text, created by the inner party, is an attack on everything the Party stands for. It has no practical value, but does offer the Party a way to single out the most rebellious in the population.
In 1984, thoughtcrime is the name given to negative or unorthodox thoughts about the Party. In Oceania, it does not matter that these thoughts are unspoken; merely thinking something bad about the Party is a crime in itself.
In Part One, Chapter One, Winston commits thoughtcrime when he writes DOWN WITH BIG BROTHER in his diary. This is a criminal act because he is expressing his desire to see the Party destroyed, and as a Party member, he should think the very opposite.
In the next chapter, there is another example of Winston's thoughtcrime:
To the future or to the past, to a time when thought is free, when men are different from one another and do not live alone—to a time when truth exists.
This is another of Winston's diary extracts in which he imagines a free, almost utopian society in which independent thought and behavior are encouraged. Again, he is expressing his discontent with life under the Party, and, as he later acknowledges, this makes him a dead man walking.