What is the significance of Hamlet's "Alas, poor Yorick!" speech?
In Act V, scene i, of Shakespeare's Hamlet, Hamlet and Horatio are in the graveyard, where two "clowns" ("rustics") dig Ophelia's grave. Horatio and Hamlet have just arrived, not yet aware of the funeral taking place for Ophelia, the grave for Hamlet's sweetheart. Death is strongly themed in this scene.
Hamlet is talking to the gravediggers, wondering at the souls lost, the bodies that have been laid to rest there. When Hamlet realizes that he holds the skull of Yorick, the court jester, he is reminded of how fleeting life is. This is an opportunity for the audience to see into Hamlet's past: the happy years when his father was alive, when he so enjoyed the company of the jester, and when life was much less complicated than it is now.
Hamlet tells Horatio that the jester told wonderful jokes and had a great imagination.
Alas, poor Yorick! I knew him, Horatio: a fellow
of infinite jest, of most excellent fancy, ... (177-178)
He talks about the many times he played with Yorick, climbing on his back. These playful and loving images, reminiscent of joyous days of Hamlet's childhood, give way to the horror of death, and the mood changes dramatically. Hamlet sees what has come of Yorick, of the man he kissed innumerable times—and the reality makes him sick.
Considering the skull, Hamlet speaks as if he were talking to a living Yorick, asking him where his jokes are now, his songs, his laughter, his gift of entertaining an audience until everyone's sides split with mirth at his antics. He recognizes that Yorick is no longer what he was; death has overtaken him. But Hamlet asks if Yorick wouldn't go to Gertrude ("her ladyship") to tell her that no matter what disguise she wears, death will come for her as well: She, too, will find her way into the ground as has Yorick.
Now get you to my lady's chamber, and tell
her, let her paint an inch thick, to this favour she must come. (185-186)
The theme of mortality is strongly addressed in this scene. The gravediggers have been joking about death as they dig Ophelia's grave, and they discuss matters of the death of royalty. (This infers that in death, the nobility is in some way better off.) However, in Hamlet's speech, he affirms one's sense that death is the great equalizer. All things born, regardless of one's position in society, must die. As with Yorick, whom Hamlet so loved: None will escape the fate each mortal man must face. This seems to foreshadow Hamlet's last line in the play:
The rest is silence. (V.iii.270)
Hamlet knows more each day of man's limited life. In this way he has grown up since Old Hamlet's death. Hamlet understands deeply that all roads lead to death. One day, having lived a life with things he believes were so important, he will die and it all will mean nothing: all death ends in the silence of every man.