He introduced around 600 words in Hamlet that he had never used before, two-thirds of which he would never use again

The roughly 4,000 lines in the play [Hamlet] ended up requiring nearly the same number of different words (for comparison’s sake, Marlowe’s Doctor Faustus and The Jew of Malta each use only about half that number). Even the 14,000 or so different words or compounds that Shakespeare had already employed in his plays (by the end of his career that figure would reach about 18,000) proved insufficient. According to Alfred Hart, who painstakingly counted when and how Shakespeare introduced each word into his work, he introduced around 600 words in Hamlet that he had never used before, two-thirds of which he would never use again. This is an extraordinary number (King Lear, with 350, is the only one that comes close; in the spare Julius Caesar only seventy words appear that Shakespeare had not previously used).

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 320

The same ingredients, viewed from the perspective of musical comedy, make perfect sense

Shakespeare chose to write more songs – five in all, three sung by adults, two by boys – than he would in any other play. Thinking of As You Like It as an embryonic musical may help explain why critics have had such a hard time with its meagre, episodic plot, its rich vein of contemporary satire, its over-the-top climax where the god Hymen enters, and all its song and dance. The same ingredients, viewed from the perspective of musical comedy, make perfect sense.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 251

Those familiar with his sources expected Cordelia to live

When Shakespeare had King Lear enter with Cordelia dead in his arms, he caught his audience by surprise, all the more so because those familiar with his sources expected Cordelia to live.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 238

Issues Elizabethans confronted in their world and in the theatre – assassination, succession, tyrannicide, holidays – were not only steeped in but produced by religious division.

Since the end of the seventeenth century critics and editors of Julius Caesar have focused almost exclusively on the play’s unforgettable characters and gripping political drama. From their perspective, the religious bits that surface throughout the play were ‘palpable blunders’ and for a long time they did their best to ignore or repair them. When, in 1693, Thomas Rymer condemned the play’s anachronisms as ‘a sacrilege’, his language ironically registers the extent to which a fixed notion of what Shakespeare’s Roman play ought to be – classical, political and pagan – had displaced the mix of religion and politics that Shakespeare’s audience would have taken for granted. Issues Elizabethans confronted in their world and in the theatre – assassination, succession, tyrannicide, holidays – were not only steeped in but produced by religious division. Part of Shakespeare’s genius was discovering in Plutarch’s old story the fault lines of his own milieu.
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Moral qualms aside, the real problem with political assassination for Elizabethans – and Shakespeare’s play makes this abundantly clear – was that it unleashed forces that could not be predicted or controlled. Assassination was linked with chaos, blood-letting and potential civil war because this was what it invariably led to. However noble Brutus’ motives, however morally and politically justified his actions, it would have been clear to many in Shakespeare’s audience that he hadn’t thought things through. Critics who fault Julius Caesar for being a broken-backed play, who are disappointed by the final two acts and who feel that the assassination takes place too early in the action, fail to understand that the two parts of the play – the events leading up to the assassination and the bloody civil strife that follow – go hand in hand.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 156 and 163

This whole section on how deeply Julius Caesar is informed by the French Wars of Religion was fascinating.

Bizarrely, modern-day editors, who ought to know better, have followed suit

This unusual epilogue survives by accident – or rather, due to carelessness. The Second Part of Henry the Fourth was published less than two years after this. When the manuscript was passed along to the printing house, both versions of the epilogue were bundled with it. The compositor setting type, unsure of what to do, printed both but left an extra bit of space between the Whitehall and Curtain versions. Had he thought about it more, he might have realized that it made no sense for the speaker to kneel to the Queen midway through the epilogue and then spring up again. When the compositor of the 1623 Folio came upon this crux he too decided not to choose between the two but also melded them into a single epilogue, though he at least tried to mend things by moving the prayer to the Queen to the end of the epilogue. Bizarrely, modern-day editors, who ought to know better, have followed suit, leaving the confusion intact and obscuring why and how Shakespeare redirects his art at this time.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 41

Shakespeare and his fellow dramatists were writing for the most experienced playgoers in history

In 1600, in an England of four million, London and its immediate environs held a population of roughly two hundred thousand. If, on any given day, two plays were staged in playhouses that held as many as two to three thousand spectators each, it’s likely that with theatres even half-full, as many as three thousand or so Londoners were attending a play. Over the course of a week – conservatively assuming five days of performances each week – fifteen thousand Londoners paid to see a play. Obviously, some never went at all, or rarely, while others – including young and generally well-to-do law students at the Inns of Court – made up for that, seeing dozens of plays a year; but on average, it’s likely that over a third of London’s adult population saw a play every month. Which meant that Shakespeare and his fellow dramatists were writing for the most experienced playgoers in history.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), 9-10

How in the course of little over a year he went from writing The Merry Wives of Windsor to writing a play as inspired as Hamlet

This work, then, grew out of frustration with how much I didn’t know and frustration with scholars of all critical denominations who never quite got around to addressing the question I found most pressing: how, at age thirty-five, Shakespeare went from being an exceptionally talented writer to being one of the greatest who ever lived – put another way: how in the course of little over a year he went from writing The Merry Wives of Windsor to writing a play as inspired as Hamlet.

J. Shapiro, 1599: A Year in the Life of William Shakespeare (2005), loc. 152