Winston commits a thought crime by writing what statement in his diary?
Well, the scary thing about the world of 1984 is that the phrase was a Thoughtcrime whether he wrote it down or not; it was a Thoughtcrime if he even just thought it. What's more, lots of what he wrote in the diary would probably have been considered a Thoughtcrime. That said, the big Thoughtcrime was writing "Down With Big Brother," over and over. Go Winston!