In his speech to Rosencrantz and Guildenstern in [II. ii.], Hamlet contrasts how the world is with how it seems to him. Why does it seem that way?
The theme of "Appearance versus Reality" is to be found throughout Hamlet and Hamlet's interaction with Rosencrantz and Guildenstern is an example here in Act II Scene ii. Hamlet is telling them to their face, but obliquely, that he knows they are lying about their purpose in visiting Elsinore. They pretend to be his friends, but Hamlet shuts them down and demands an answer:
"You were sent for; and there is a kind of confession in your looks which your modesties have not craft enough to colour."