What purpose does the prologue serve in Romeo and Juliet? At the beginning of Act One, Scene Four, Shakespeare has Benvolio say something about prologues and their purpose. What does this mean?
The prologue in Romeo and Juliet provides important exposition for the audience or reader. Because the play begins in media res—or, "in the middle of things"—it is necessary to provide some background information to make sense of what follows. From the prologue we learn that the Montagues and Capulets are two families of similar socioeconomic backgrounds and reputations ("Two households, both alike in dignity...") who are engaged in a very old feud that continues to wreak havoc across Verona ("From ancient grudge break to new mutiny, / Where civil blood makes civil hands unclean."). We are introduced to the protagonists of the play: the "star-cross'd lovers" who are members of these rivaling factions. We also learn prematurely of their deaths. This is all critical information since the very next scene is, in fact, a brawl between the Montagues and Capulets—one that might seem a bit random or antagonistic without context.
You might wonder why Shakespeare would choose to give away all this information (particularly the end of the play itself!) before the action has even started, and in this case it's significant to remember that this material was meant to be seen on stage and not read. The prologue, which states that there will be "two hours' traffic of our stage," lets a Shakespearean audience (which largely consisted of people packed together in the cheap standing section) how long the play will last—and how long they'll have to hold off from fidgeting!
It is ultimately a testament to the staggering emotional gravity of this work that audience members who already know how the story resolves were (and still are!) happy to sit through the whole performance anyway. In our modern age of "spoiler alerts," it is also fascinating that contemporary audiences who are so overly-familiar with the basic plot of this story and who have seen it re-made and adapted a thousand times over still flock to the original text. Romeo and Juliet is indeed a classic.
As for Benvolio's remark about arriving at the Capulet ball "without-book prologue": Benvolio is simply answering Romeo's question here ("What, shall this speech be spoke for our excuse? / Or shall we on without an apology?") and weighing in on the use of having one's entrance announced. Romeo and his crew will sneak into the ball without pomp and circumstance, and they will allow the other partygoers to size them up "by what they will." This is also a sly reference to the play's prologue. Whereas we begin the play knowing exactly what will be set forth, we enter this scene without this same knowledge. This is a subtle way of suggesting that the tides are about to shift for Romeo and that the events to follow will be a turning point.
The prologue serves as an introduction to events which are about to unfold on stage. It is similar to a thesis statement in an essay and is much like a preview to a movie to pique an audience's interest--Shakespearian style. The prologue serves to whet the audience's appetite.
Benvolio makes the following statement:
"The date is out of such prolixity:
We'll have no Cupid hoodwink'd with a scarf,
Bearing a Tartar's painted bow of lath,
Scaring the ladies like a crow-keeper;
Nor no without-book prologue, faintly spoke
After the prompter, for our entrance:"
What he is saying is that their arrival at the Capulet's masked ball will be unannounced, unlike when Cupid, bearing a toy-bow made a speech to introduce a group of ladies to an audience. Their arrival will be intrusive and since they are enemies of the Capulets, they would not want their arrival to be made public. Also, because they will be in disguise, no one will recognise them and their arrival would not, therefore, be announced anyhow.
Benvolio is referring to the general nature of plays where an actor appears on stage assisted by a prompter who reads from a book (obviously the text of a play) to help the actor should he/she forget his/her lines. In this instance, however, there would be no such prompter or book.
Furthermore, he is also making an indirect reference to the prologue of this play, where the audience is informed. Their audience, however, will be unprepared and would therefore not know what to expect.
In the play Romeo and Juliet, the audience knows the outcome of the play even before we meet the main characters. The chorus begins the play by presenting the Prologue. This introduction to the play sets up the story by explaining the plot that is about to take place. The chorus explains the centuries long feud that exists between the Montagues and the Capulets that will end after a child from each of the warring families falls in love with one another. However, this will not be our typical happily ever after love story as the two families will only have peace and come together after the deaths of the innocent children.
From forth the fatal loins of these two foes(5)
A pair of star-cross'd lovers take their life;
Whose misadventur'd piteous overthrows
Doth, with their death, bury their parents’ strife.