are extremely complex. (They, too, also get more complicated the closer we look!) To say "the main theme ofRomeo and Juliet is ____" or "Shakespeare is trying to teach us this: ____" is to oversimplify the intensity and nuance of the work. The best we can do is identify a particular theme, like the Free Will vs. Fate idea that e-martin mentioned, and track its development through the plot via specific illustrative examples. But a true scholar would be aware that there are multiple themes, and it is the interplay/tension of those ideas that, along with the reader's personal experience and interpretation, result in the message, effect, and therefore "teaching" conveyed by the text.

Shakespeare is highlighting the explosive energies that intense passion can bring. We see this in the love between Romeo and Juliet, the feud between the Montagues and the Capulets, the anger of Tybalt and the excesses of Mercutio. Intensity of passion is what makes life exciting, but can have tragic consequences.

This play, like Macbeth, seems to explore the notion of "free will versus fate". Though Romeo and Juliet choose to act as they do there is also a strong implication that the two are fated to their particular doom. 

Here the doom is not supernatural but completely natural. It is a doom born out of human nature. In Macbeth the idea of fate is represented by supernatural forces (the witches).

In both plays an outcome is defined before the characters have made their decisions, raising a question as to how avoidable the outcome truly is, how much an individual can change his/her fate, and how set an individual's path may be by forces outside of his/her control. 

Shakespeare is saying many things about human nature throught Romeo and Juliuet. One of his main themes is young love and how moving too quickly can lead to a tragic end. Shakespeare makes it clear that Romeo is too immature to truly love Juliet the way he says he does, and his haste in his actions lead to the death of both of them. This theme is, of course, entertwined with other themes, such as adult ignorance and irresponsibility. Yes, Romeo and Juilet were too young and didn't know each other long enough to really be in love, but the adults should have been more responsible and paid more attention to what their children were doing.

One good way to determine a writer's message, or theme, is to look at how characters change over the course of a story. Romeo and Juliet themselves don't change much, they are impetuous youngsters all the way through. But at the end, as a result of the tragic events, their families, the Capulets and the Montague's, vow to end their feud.

So the theme, which could be stated in many possible ways, should have something to do with the fact that sometimes it takes a significant tragedy to overcome a problem (the feud). You could also focus on the idea that parents and families can be blind to their children's needs when the are distracted by worldly concerns.

Another theme is the over-whelming nature of new love. Romeo and Juliet are swept off their respective feet by love at first sight and this emotional impact affects all of their choices and actions from there on out. They believe in their love and their ability to have their love be able to overcome all of the hurdles their relationship faces.

I think that what he is saying is that human beings are too impulsive and ruled by their emotions.  We see this in practically every character in the play.  So many characters are themselves harmed (or harm others) because they cannot prevent themselves from acting based solely on emotional impulse (as opposed to calm reasoning).

I think Shakespeare could be trying to say several things. One might be a commentary on the foolishness of squabbles like that between the Montagues  and the Capulets, which have the effect of consuming the two lovers, as well as Mercutio, Paris, and Tybalt. Shakespeare may also be trying to suggest something about love, though I'm not clear as to what that is, because I've never been sure about how he views their deaths at the end. In a sense, they die rather than yielding to the world, but in another sense, their forbidden love can only end one way. Fate is also a strong theme in this play, as the actions of the characters seem to lead step by step to the final tragedy.

The "human condition" defines humanity's darker nature. While humanity has the ability to be benevolent, "loving," and "selfless," we also have a recognized darker side ("Definition of The Human Condition," worldtransformation.com). Humanity's darker side, of course, has the capability of being evil, including creating war, committing murder, and even possessing the ability to hate. Hatred and murder are the aspects of the "human condition" that Shakespeare explores most in Romeo and Juliet.

Romeo is one character in which we can see the "human condition" portrayed. Romeo has a great ability to love. He even falls in love very easily, as we see with both Rosaline and Juliet. However, he is also characterized by Shakespeare as being so driven by his emotions that he is rash and impetuous. His emotional drive creates the conflicting actions that we see him especially demonstrate with respect to Tybalt. In Act 3, Scene 1, when Romeo first comes on stage, he is filled with love for Tybalt due to the fact that, unbeknownst to Tybalt, Romeo and Tybalt are now family members. Romeo tries to pacify Tybalt, declaring that he never "injured," or insulted Tybalt, but instead "love thee better than thou canst devise" (III.i.67-68). Romeo's declaration of love shows Romeo's capacity to love as a human being. However, when Mercutio picks a fight with Tybalt, resulting in Mercutio's own death, Romeo's love for Tybalt quickly turns into raging vengefulness. When Tybalt returns on stage, we see Romeo's fury and desire for revenge in the lines,

Alive in triumph, and Mercutio slain?
Away to heaven respect lenity,
And fire-ey'd fury be my conduct now! (123-125)

After Tybalt fled the scene immediately after stabbing Mercutio, Romeo had the opportunity to run away from the fight as well. Romeo knew that the Prince's judgement over Tybalt would have been severe, resulting in Tybalt's death. He could have chosen to let the power of the law take over instead of choosing to avenge Mercutio himself. It is Romeo's rash, impetuous emotionalism that drives him to fury and revenge. Romeo's ability to feel both love and vengeful fury is of course an example of Romeo's "human condition."

This play can teach its audience about the terrible lengths to which we will often go for love, for pride, or for power.  It isn't just about the teenagers who fall in love at first sight; although their story has value, too.  The play also focuses on the terrible, but human, behavior of the Capulets and Montagues in terms of their feud, a grudge that is so long-standing that no one even seems to discuss the disagreement with which it began.  For family pride then, the feud continues, and it is responsible, ultimately, for Tybalt's death, as well as the deaths of Mercutio, Paris, Romeo, and Juliet.  Were it not for the ridiculous and proud fight between the family patriarchs, Tybalt would not have felt dishonored by Romeo's presence at the party.  He would not have challenged Romeo, and thus Mercutio would not have become involved (which he does, also, for honor).  Romeo would not be banished for slaying Tybalt, he would not have killed Paris and Juliet's tomb, and the tragedy could not have unfolded as it did.  

Further, Lord Capulet's proud insistence on his daughter's absolute obedience when he orders her to marry Count Paris denies her speech, opens a gulf between Juliet and her parents, and makes her desperate.  His need to rule over her, and his unwillingness to hear her at all, leads, ultimately, to her death as well as Romeo's and Paris's.  

In the end, most of adults behave immaturely and selfishly.  They think only of themselves and their own pride,  They have little care or concern for others, and they drive their children to desperate lengths.  In terms of human behavior, we see that humans will most often act in order to retain or acquire power or to preserve their pride.  We see how the practice of such selfish behavior leads only to tragedy and pain.  From this play, we learn that we often fail to consider all the possible repercussions of our selfish behaviors and how they can, and often do, return to plague us in the end.

An instance of storytelling occurs in Romeo and Juliet when Romeo, walking with Benvolio and Mercutio to the Capulet masquerade ball, expresses reservations about going based on a dream he had a night before.

Mercutio, who is determined to get Romeo to the ball in hopes he will find another girl and stop mooning over Rosaline, tells him that dreams often lie. Romeo tells Mercutio that dreams often tell truth. Mercutio then goes on to tell the story of Queen Mab, a tiny fairy who rides around in a tiny coach. The spokes of the wheels are made of spider's legs, a somewhat creepy image. Queen Mab causes people to dream of what they lust for, be it money or sex.

When Romeo tells Mercutio he is talking of "nothing," Mercutio tells Romeo that is right, because dreams are nothing. Nevertheless, Romeo's dream leaves him with a feeling of foreboding about the party. We are left to wonder who is right, knowing Romeo is coming to a bad end: do dreams tell truths or are they nothing?

Mercutio's story of Queen Mab shows some of the complexity of love. Romeo, who is in love with the idea of being in love, sees nothing wrong in it, but to the more cynical Mercutio, love can easily fall into being a crude lust. Mercutio thus suggests that maybe what Romeo calls love is more than a little bit tinged with lust. Mercutio throughout the play—until he is killed—wants Romeo to be less softheaded, less likely to fall head over heels in love.

He will persist on this theme, for example, in act 2, scene 4, by having fun weaving the false story of Juliet's nurse being a whore the morning the nurse comes to discuss the wedding with the friar. In doing this, Mercutio creates a comic if cruel form of jest that annoys the nurse no end—but the larger point is that these stories are Shakespeare's way of introducing some nuance into what love really is: it is the "pure love" that Romeo fashions it or is more sordid?

Second, the story of Romeo and Juliet's star-crossed (doomed) destiny is laid out to the reader in the Prologue, suggesting it very much to be a story, a fiction. This story of the offspring of feuding families falling in love runs smack into and complexities the story the Montagues and Capulets tell themselves of the other "side" being bad while their side is "good."

As it happens, both sides contain good. Stories complexity three issues at least in the play: the meaningfulness or lack thereof of dreams, the nature of love versus lust, and the tendency of people to see their enemies as all evil and themselves as all good.

Shakespeare’s Romeo and Juliet certainly explores issues relating to human nature. Let’s look at some examples to get you started.

We might note first that the play reflects on the human tendency toward grudges and vengeance. People are easily offended and then hold onto that offense sometimes almost indefinitely, even after the reason for it has long been forgotten. Look at the feud between the Capulets and Montagues. No one seems to remember what they are fighting about, but they certainly know they are fighting, and they do it to the point that it causes disruption throughout the city. Sometimes, people actually enjoy conflict, but they certainly do not like the tragic consequences it brings.

We should also look at how the play presents the fickleness of human nature. When the play opens, Romeo is madly in love but not with Juliet. He thinks that if he does not get to be with Rosaline, he will die. But with one glimpse of Juliet, he forgets all about the woman he has sworn to love for eternity. He turns his full attention to Juliet instead. She is just as quick to fall for him, revealing how a bit of attention can turn a person’s head. Romeo and Juliet are not the only fickle ones, though. Notice how Juliet’s father is against her marriage to Paris until his daughter is a couple of years older. Yet later in the play, he is ready to marry her off the next day.

Other elements of human nature appear in this play, too. Think, for instance, of Friar Laurence’s difficulty determining the wisest course of action or of Mercutio’s cynicism. You might also explore the quality of despair and the temptation of seduction, both of which people tend to fall into easily at times.