‘O for a Muse of fire’: so begins the Prologue to William Shakespeare’s Henry V. The Prologue is spoken by the Chorus, and the speech sets the scene for the historical drama that will follow; it also makes reference to the very theatre in which Henry V was first performed, which makes it doubly notable as a speech.
As is our fashion here at Interesting Literature, we’ll go through the ‘O for a Muse of fire’ speech a section at a time, summarising its meaning and offering an analysis of its language and imagery. So, if you’re ready …
O for a Muse of fire, that would ascend
The brightest heaven of invention,
A kingdom for a stage, princes to act
And monarchs to behold the swelling scene!
The Chorus begins by calling for ‘a muse of fire’: that is, inspiration as bright and brilliant as the element of fire, which was regarded as the brightest of the four classical elements (the other elements being earth, air, and water). Such a muse would allow the Chorus to attain the highest peaks of creativity and imagination (‘invention’ should be pronounced as four syllables in keeping with the iambic pentameter: in-ven-shee-un).
Such a ‘muse of fire’ would enable the Chorus to re-create history before the play’s audience: the stage would become a whole kingdom, the actors would be the princes they portray, and actual monarchs would watch the majestic spectacle as it played out before them.
Then should the warlike Harry, like himself,
Assume the port of Mars; and at his heels,
Leash’d in like hounds, should famine, sword and fire
Crouch for employment.
If such a feat were possible, King Henry V himself, great warrior, in his own great manner would take on the demeanour of the god of war himself, Mars (from Roman mythology). At the King’s heels, kept on a leash as dogs are, you would find famine, sword, and fire (three traditional instruments of war, as T. W. Craik observes in his notes to the excellent Arden edition, “King Henry V” (Arden Shakespeare: Third)), crouched ready to be deployed by him.
But pardon, and gentles all,
The flat unraised spirits that have dared
On this unworthy scaffold to bring forth
So great an object: can this cockpit hold
The vasty fields of France? or may we cram
Within this wooden O the very casques
That did affright the air at Agincourt?
The Chorus begs the ‘gentles’ (ladies and gentlemen) of the audience pardon, because he knows that this ‘scaffold’ or stage is ‘unworthy’ to bring such a vast subject to life. It is but a ‘cockpit’: a word which originally referred to the small arena in which ‘cocks’ or chickens would fight (cockfighting was a hugely popular pastime throughout the Middle Ages and Early Modern period).
The Chorus’ reference to ‘this wooden O’ is usually interpreted as a reference to the newly built Globe theatre, which 
Shakespeare’s company built in 1599, shortly before Henry V was first performed. ‘Casques’ refers to the helmets worn by soldiers on the battlefield at Agincourt in October 1415 (a key set piece in Shakespeare’s play).
O, pardon! since a crooked figure may
Attest in little place a million;
And let us, ciphers to this great accompt,
On your imaginary forces work.
The Chorus again apologises to the audience before the play even begins. He goes on to reason that, since one figure can represent a million on the small stage, the audience should permit the actors to go to work on the audience’s imaginations.
There is a clever piece of wordplay on ‘figure’ here, suggesting the figure or number of ‘zero’ as well as a human figure; this chimes with ‘ciphers’ a couple of lines later, which literally means ‘zeroes’. Shakespeare is drawing on the world of tables and bookkeeping, where a zero at the end of a row of figures does serve to represent a big number such as one million (1,000,000). ‘Crooked’ further underscores the inadequacy or smallness of the theatre company in representing the vastness of what took place between the armies at Agincourt.
Suppose within the girdle of these walls
Are now confined two mighty monarchies,
Whose high upreared and abutting fronts
The perilous narrow ocean parts asunder:
Piece out our imperfections with your thoughts;
In other words, ‘imagine, if you will, that within this theatre there are two great kingdoms with cliffs along their coasts (i.e., England and France) separated by the English Channel; and extend or fill in the gaps of our representation with your minds.’ So, in short, let your imaginations supply what we physically cannot in such a small space and with a small group of actors.
Into a thousand parts divide one man,
And make imaginary puissance;
Think when we talk of horses, that you see them
Printing their proud hoofs i’ the receiving earth;
Although the Chorus said ‘divide’, he means ‘multiply each actor by a thousand’. Imagine there is ‘puissance’ or armed might and force present. And when the actors talk of horses, the audience are asked – like something out of Monty Python and the Holy Grail – to imagine the actors are riding said imaginary horses, which are stomping along the ground.
For ’tis your thoughts that now must deck our kings,
Carry them here and there; jumping o’er times,
Turning the accomplishment of many years
Into an hour-glass: for the which supply,
Admit me Chorus to this history;
Who prologue-like your humble patience pray,
Gently to hear, kindly to judge, our play.
The Chorus concludes his speech by referring to the illusion of all theatre: ultimately, every play involves the audience’s participation in the creation of the illusion, and letting their imagination supply what cannot be presented literally on stage. So the playgoers’ imaginations must deck out the kings portrayed on stage, and imagine them travelling from place to place and jumping forward over several months and years. The play must condense the action (which took place over a number of years) into a play that runs for just a few hours.
He entreats the audience to accept him as the commentator on the history they will witness, begging their patience as they hear (and, he hopes, kindly judge) the play put before them.
Craik notes that it was ‘the usual Shakespearean expression’ to refer to hearing rather than seeing a play, and this is one reason why Shakespeare’s language is so rich with imagery: to summon forth into the audience’s imaginations the spectacle of what cannot be literally put before them, such as those vast armies and battles. So hearing the play was, in many ways, more important even than having a good view.
The Chorus concludes his Prologue, and makes way for the action of Act 1. And with that, Henry V gets underway, with all of the ‘mighty monarchies’ and actions of ‘warlike Harry’ that he had promised his ‘muse of fire’ to make possible.