For some period of time, Winston has experienced how it was to be tortured. Therefore, when he has been moved to a more comfortable room where he has more space to think and freshen his mind, as the torture eases. The passage shows that Winston is "writing down the thoughts that came into his head" and the first slogan is "FREEDOM IS SLAVERY" almost without pausing this gives an expression that he rushes his mind to think in that essence. So with a continuous way of thinking he restricted his mind to think forward and not looking back and changing his mind to his old beliefs, so then he immediately writes the second slogan which is "TWO AND TWO MAKE FIVE" it is rather bizarre or unexpected because, those were the things that he opposes to. And there is when he began to assess himself in order to think the way the Party wanted him to behave. It was clear that he made the decision by forcing his own thoughts to believe in things that are contradictory to his previous belief. In the description it is shown how "the pencil felt thick and awkward in his fingers" and the letters are described as "large" and "clumsy" as he is writing by force. .
"But then there came a sort of check. His mind, [] seemed unable to concentrate" the first two sentences indicate how Winston is somehow absent minded and unaware of what he has written, "he knew that he knew what came next, but for the moment he could not recall it". The next sentence describes the way of his mind recalling the next slogan, which is "GOD IS POWER" by his reasoning, other than his own mind that automatically tells him the order of what comes next.
"He accepted everything, the past was alterable. The past never had been altered. []" In this paragraph consist of short sentences which refers to Winston's denial towards the real facts and the Party's real facts.