Hamlet is fundamentally a play about seeking the truth. The opening scene is a miniature play which introduces the questions that will have to be answered throughout the rest of the work. Barnardo asks, "Who's there?" and is answered by Fransisco with, "Nay, answer me. Stand and unfold yourself" (1.1.1-2). The entire plot is encapsulated in these words, with Hamlet struggling to know who is really standing across from him, and with his own unfolding of himself to the audience. Thus Hamlet will seek to know the truth about whether the ghost is really his father while simultaneously trying to figure out who he himself is as a person.
The ghost presents a figure of antiquity that contrast strongly with the more modern Denmark ruled by Claudius. Barnardo comments, "Looks it not like the King?" (1.1.41), responding to the image of Old Hamlet as the old warrior, wearing complete armor and holding a truncheon. In fact, we are told he looks the same as when he defeated Old Norway. Even the language of the ghost relies on mythology to compare things, "I find thee apt, / And duller shouldst thou be than the fat weed / That rots itself in ease on Lethe wharf" (1.5.31-33). This conflict between the new world which has defeated the old world is made clear by Hamlet, who comments, "That thou, dead corpse, again in complete steel" (1.4.33). Later this contrast will come across even more clearly, in the choice of armor and weaponry. Whereas Old Hamlet appears wearing full armor, the new weapons will be the rapier and the fencing armor, showing how combat is made in sport rather than in war.
Claudius represents the voice of this new society; he is the perfect new politician and stands in contrast to Old Hamlet. This is evidenced strongly by their choice of words: Old Hamlet is of the old Senecan tradition and uses repetition, Claudius uses prose. Claudius further prefers to define himself with the words, "though", "ourselves", and "therefore", as opposed to ghost who uses "I". In true political vein, Claudius' words flow smoothly but the his meaning runs counter to the words. For instance, only by listening closely does the audience realize that he is speaking about incest but hiding it with the language he chooses. We have to listen closely to realize there is something wrong with what he is saying, such as when he contradicts himself: "With mirth in funeral and with dirge in marriage" (1.2.12).
One of the most interesting parallels is the non-play concerning Fortinbras, a
man whose story is told only be others until the very end. He is almost a perfect parallel to Hamlet: his father has been murdered, his uncle has taken the reigns of power, and he desires revenge. However, in contradiction to Hamlet, he is also a man who is able to act. We learn in the first act that he has raised an army to attack Denmark, and by the final act he actually appears with his army. Hamlet's growth as a character can in many ways be seen as a progression to what Fortinbras is able to do, namely take action. Claudius will underestimate Fortinbras' army, much the way he underestimates Hamlet's madness, thereby causing his own destruction.
The clothes that Hamlet wears during the opening scenes indicate both his state of mind and also his perception of his mother and Claudius. Queen Gertrude begs Hamlet to remove his black clothing, "Good Hamlet, cast thy nightly colour off" (1.2.68). The clothes take on two separate meanings here, the first of which deals with melancholy. Melancholy was traditionally viewed as the cause of madness by physicians of Shakespeare's time, and thus Hamlet's wardrobe serves to foreshadow his future madness, or at least lends credence to it. The clothes also indicate that Hamlet is an actor. He is not still in mourning for his father, evidenced by his comment to his mother that mourning clothes do not necessarily mean he is still mourning. The inference that can be drawn from this is that Hamlet thinks that the king's clothes do not mean he is a real king. Hamlet's rejection of his clothes after the first act lends credence to the argument that he is merely acting, as do his words in which he tells the audience that he will no longer pretend the way Claudius does.
Hamlet is also a play about watching plays, a job that can quickly become dangerous. There are the watch sentries watching the ghost, Polonius watching Hamlet, Claudius watching the Mousetrap play, etc. All of this ties in with the fact that Claudius and Gertrude are actually a player king and a player queen, both literally and figuratively. Hamlet alone is able to overcome this by not being illusory. He tells his mother, "Seems, madam? Nay, it is. I know not 'seems'" (1.2.76). This "seems" also plays on the phonic similarity of "seems" and "scenes". Hamlet is basically refusing to be called an actor. He states, "These indeed 'seem', / For they are actions that a man might play" (1.2.83-84). His rejection of illusion is based on a rejection of fakeness and lies, not merely acting. Thus his feigned madness, while at first glance an form of acting, is actually lucidity, Hamlet uses his madness to speak truthfully without being punished.