Complex sentence: Boxer is quite dim; he can only remember the first four letters of the alphabet which links to the fact that Boxer represents the working-class citizens who were fooled and tricked into thinking that their life would be a Utopia.
Split into simpler sentences: Boxer is quite dim; he can only remember the first four letters of the alphabet. He represents the working-class citizens who were fooled and tricked into thinking that their life would be a Utopia.