These indeed “seem”
For they are actions that a man might play
(I.ii.)

When Gertrude asks Hamlet why he still seems so upset about his father’s death, Hamlet takes offence at her use of the word “seems.” He describes his clothes and appearance at some length before agreeing—strangely—that everything he’s said so far could indeed be an actor’s performance. “But,” he adds, “I have that within which passes show” (I.ii.). Both Hamlet and the audience will have to wrestle with the difficulty of telling pretend or performed feelings from the real feelings which characters cannot “show”.

The play’s the thing
Wherein I’ll catch the conscience of the King
(II.ii.)

When the Players arrive, Hamlet decides to stage a play in which Claudius’s crime is represented, because Hamlet has heard that seeing their own crimes on stage sometimes makes people reveal their guilt. Hamlet believes very strongly in the power of theatre to touch people’s innermost feelings. Nevertheless, Hamlet’s decision to stage a play is a strange one. He has struggled over and over with the difficulty of discovering a person’s real feelings from their outward presentation, and yet he seems to believe he will be able to discover Claudius’s guilt by watching his face at the play. This line suggests that Hamlet is not being entirely honest with himself. The play may be just another delaying tactic.

The purpose of playing[…] is to hold as ‘twere the mirror up to Nature
(III.ii.20-22)

Before the Players go on stage, Hamlet gives them a lecture about acting. This line shows us that Hamlet is a true theatre-lover, but it also reveals his awareness of the slippery distinction between reality and performance. The thrust of Hamlet’s lecture is that acting should be as close as possible to reality, in order to reflect reality back at the audience. As Hamlet continues, however, the closeness of Hamlet’s own performance to reality troubles us: we find it more and more difficult to tell the difference between Hamlet’s real feelings and his performed madness.

What’s Hecuba to him, or he to her,
That he should weep for her?
(II.ii.)

As Hamlet watches the First Player perform a speech about the legendary Queen Hecuba, Hamlet is amazed to see the Player begin to weep. Hamlet compares himself to the Player: while the Player weeps for a person he never knew, Hamlet has so far done nothing to avenge his own murdered father. This contrast creates a whole new layer of doubt for Hamlet. Can his feelings about his father be real if they are not making him act? When performed feelings are so convincing, how can he tell between a performance and reality?

Call the noblest to the audience
(V.ii.)

In the play’s final moments, the new King, Fortinbras, agrees to Hamlet’s dying request—relayed by Horatio—that Hamlet’s story should be told again. Fortinbras gives the necessary orders in strikingly theatrical language, creating a sense that although Hamlet is ending, another play is about to begin. Hamlet’s body will be carried “to the stage” (V.ii.) and a new audience will try to decide the truth of Hamlet’s story. The last moments of the play suggest that in the world of Hamlet, there is no end to uncertainty, and no end to performance.