Thus Hamlet says, "that skull had a tongue in it, and could sing once: how the knave jowls it to the ground, as if it were Cain's jaw-bone that did the first murder." This aspect of the scene also shows how Hamlet, whether he likes it or not, constantly returns to the same themes whatever situation he is in. The fact that the jawbone could be that of Cain, leads him to the subject of murder which in turn leads him to the fact that he believes his father was murdered by his Uncle and mother.
Hamlet makes fun of all the titles, property and pride that make him a "Prince", but which will eventually disappear into that great equalizer. The fact that he has felt uneasy with the idea of being a royalty occurs through the play and is persistent in this scene as he looks at skull that might have been "a lawyer's" or a "great buyer of land". They are all equal now within death.
The theme of death taking away the innocence of childhood appears as Hamlet says the famous line, "alas, poor Yorick, I knew him well". Death's bit is even more keen when it has occurred to someone that we fondly remember from out childhood. Again, Hamlet asks a series of questions that he knows the answer to before he has spoken them. These are perhaps the ultimate rhetorical questions: "where be your gibes now, Your gambols Your songs Your flashes of merriment, that were wont to set the table on a roar Not one now, to mock your own grinning." The fact that Yorick, who apparently displayed all the vitality and zest for life that Hamlet sorely lacks, is dead, makes Hamlet's own attempts to both cheat death and to avenge it seem rather pathetic.
The idea that there is no-one to "mock" the permanent "grin" that Yorick's skull is showing is perhaps the most telling fact of all. Hamlet suggests that death is mocking all mortals - so no mortal mocking is actually needed. The unfairness of death is a theme that resounds throughout the play. It is unfair that his father has been killed while his useless uncle lives. It was unfair that Polonius was killed needlessly (even though Hamlet cares little himself), and it is unfair that Ophelia has been driven to madness and hence to suicide. Death, it seems, takes those who are most innately suited to life. While those such as Hamlet himself, so thinks the Prince, are left to suffer within a tortured life.
The fact that death makes all equal is expounded upon by making the dead seem to be part of death's joke on the prideful ambitions of life. Thus the stinking skull that Hamlet is handling (that of Yorick) brings him to consideration of the fact that the "imagination trace the novel dust of Alexander, till he find it stopping a bung hole" Throughout Hamlet the title character is unable to stop his flights of imagination, and all of these turn into a kind of reduction ad absurdum in which the whole of life is rendered meaningless and somewhat laughable by the cold facts of death.
Life is very short, mutable and transient in its importance while death is eternal and majestically terrible in its permanence and resonance. Alexander may be the dust bunging up one hole or another for much longer than he was ever a great ruler. This sense of futility is resoundingly summed up within the following rhyming couplets:
Imperious Caesar, dead and turn'd to