Onstage sword fighting in Henry V during
the 2014 Shakespeare Festival St. Louis.
Image from Snoop's Theatre Thoughts.
By "invention," he means what we would call "creativity," and when he calls for a muse to provide it, he's echoing Virgil's Aeneid, which was part of the curriculum at Stratford's "grammar school," where Shakespeare studied Latin grammar and literature. The Aeneid, the fantastic tales in Ovid's Metamorphoses, the comedies of Plautus, and the tragedies of Seneca fertilized his imagination and supplied him with plots and models for his own poetry and drama. He wasn't as widely read as his friend and fellow playwright Ben Jonson—few people were—but what he read, he read deeply, which is more important.
A quick look at how he used that reading in Henry V and some related plays will show that his creative process resembled that of a screenwriter.
Shakespeare Reading (1873-74).
Image from the AMICA Library.
But like most grammar-school-educated Elizabethans, Shakespeare couldn't read Greek, so what he knew of Greek literature came primarily from reading the Roman writers who imitated it. From Seneca and Plautus, he learned the structure of Greek tragedy and "new comedy" (he used these as springboards for some early plays). From Virgil, he learned most of what he knew about Greek epic—the Iliad and Odyssey—though he also read part of the Iliad in an English translation by George Chapman. (Two centuries later, Chapman's translation of the Odyssey would inspire John Keats's "On First Looking into Chapman's Homer.") Chapman's Iliad translation heavily influenced Shakespeare's Troilus and Cressida, a strange play that deserves to be filmed by a clever, funny director. Chapman's Iliad also influenced Henry V, though that influence pales in comparison to the direct influence of the Aeneid (see Hunter 1-25 and Taylor 52-5).
Kenneth Branagh in his 1989 Henry V.
Image from Movieprop.com.
After Henry's victory, and his wooing of a French princess, the Henriad ends with an epilogue linking it to Shakespeare's "first tetralogy" of history plays. We call it the "first" tetralogy because Shakespeare wrote it first, much as someone might call Star Wars Episodes 4-6 the "first" Star Wars movies because George Lucas made them first. Just as Lucas later returned to his story with prequels, so Shakespeare returned with prequels in the Henriad or "second tetralogy." Together, the two tetralogies form a continuous epic that tells England's story from the late fourteenth century to the late fifteenth.
Georg Christoph Eimmarts's 1688 engraving (after
a drawing by Georg Jacob Lang) of Aeneas
killing Turnus at the end of the Aeneid.
Image from the Nuremberg Municipal Museums.
When Shakespeare invokes a muse in Henry V's opening lines, he alludes to the Aeneid, but his use of Virgil's epic poem goes further than mere allusion. With Henry V, the Henriad, and the entire, two-tetralogy history-play sequence, Shakespeare turns epic poetry—and history chronicles—into drama for the stage. Such transformations were one of his favorite writing strategies.
Much like a screenwriter adapting a novel, Shakespeare took material that had been written to be read (or recited) and changed it into something that could be performed. Over the course of his approximately twenty-four-year long career, in the thirty-eight plays that we know he wrote or co-wrote, he did this with classical and contemporary literature of all kinds, with poems, history chronicles, biographies, novellas, and "romances" (these were something like fantasy novels). Using these works, he created masterpieces that transcended the originals, in an entirely different medium.
Virgil was finished once he had transferred his vision to the page, but Shakespeare's vision had to be realized in a "cockpit" of a theater, by fallible actors, in front of an unruly and distracted crowd.
Next: Part Three—Imagination.