I have previously argued that merely from a reading of the text of Shakespeare’s plays, it is clear that the author of the plays is William Shakespeare.  Only he has the regional, professional, religious and family background needed to have written the specific words we find there.  Garry Wills now has an interesting analysis in this vein, drawing particularly on the use of boy actors for women’s parts (required by the law at the time), and the constraints this created for playwrights.  I am reminded of the constraints that writers of TV soap-operas work under.

Those who doubt that Shakespeare wrote Shakespeare are working, usually, from a false and modern premise. They are thinking of the modern playwright, a full-time literary fellow who writes a drama and then tries to find people who will put it on—an agent to shop it around, a producer to put up the money, a theater as its venue, a director, actors, designers of sets and costumes, musicians and dancers if the play calls for them, and so on. Sometimes a successful playwright sets up an arrangement with a particular company (Eugene O’Neill and the Province- town Players) or director (Tennessee Williams and Elia Kazan), but the process still begins with the writer creating his script, before elements are fitted around it, depending on things like which directors or actors are available for and desirous of doing the play. Producers complain that it is almost impossible to assemble the ideal cast for all the roles as the author envisioned them in his isolated act of creation. The modern writer owns the play by copyright and can publish it on his or her own, whether produced or not. None of these things was true of dramatic production in Shakespeare’s time.

Then, the process began with the actors. They chose the playwright, not vice versa. They owned the play, and could publish it or withhold it from publication. Each troupe had limited resources—often, nine to twelve adult actors (all male), and far fewer boy actors (sometimes as few as two). A Swiss traveler in 1599 saw “about fifteen” players handle the forty-five speaking parts in Julius Caesar. An aspiring playwright had to bring his idea to these actors (or their representatives) with a plot accommodated to the number and talents of the particular troupe. The parts he was describing had to be so arranged as to allow for multiple doublings. A man playing two roles could not meet himself on stage, or even come back in as someone else too soon to allow for costume and other changes (a beard, wig, spectacles, padding, and so on). “For some thirty-five years from 1547–8 plays advertise, usually on the title-page, the number of actors required and how the parts may be doubled, trebled, and even septupled.” In a 1576 morality play, The Tide Tarrieth No Man, the Vice character is told to prolong his duel “while Wantonness maketh her ready” in the tiring-house to come back out as Greediness. The plot had to be tailored for the company from the very outset.
If the actors liked the concept of a play, they would normally recommend it to a theatrical entrepreneur (Philip Henslowe was the most famous of the half-dozen or so working at a time) for an advance to the playwright while he finished the work. This advance was a loan, which the actors would pay back later, preferably from the proceeds of the play when performed. When the author finished writing his work, he read it to the company, which either accepted or rejected it at this point. If accepted, the script had to be presented to the Master of the Revels for state censorship, with payment for his reading it. He would often demand certain changes—or in some cases turn it down entirely. Only then, if cleared, could the play be put on. If, despite such screening, the play seemed seditious or libelous in the actual presentation, the actors were responsible along with the author and could be fined, suspended, jailed, even mutilated (by branding or ear cropping or nose cropping), or their theater could be closed.
Thus, in the modern theater, performers are fitted to the play, but in Shakespeare’s time, the play was fitted to the performers. If the playwright had an ongoing relationship with the troupe—like Shakespeare’s with the Lord Chamberlain’s Men (later the King’s Men)—he could create his text for the known strengths of particular actors, as Shakespeare did for the talents of the great Richard Burbage. Shakespeare wrote comic scenes in different ways for the famous clown Will Kemp and for the intellectual jester Robert Armin. He even took advantage of animal performers available to the cast. When the troupe had a trained dog, he wrote the part of Crab into Two Gentlemen of Verona. When it had a young polar bear at hand, he wrote a scene-stopper for The Winter’s Tale: “Exit, pursued by a bear.” When he had two sets of players who looked alike, he wrote The Comedy of Errors. In modern productions, with an established text, producers can shop around in a large pool of unattached actors to find two couples who are plausibly similar, but Shakespeare began with the four men already in his company and wrote the play to use them.
The trickiest job was to write for that rare commodity, the boy actors who played women. These were hard to come by and train in the brief time before their voices broke. That is why women’s parts make up only thirteen percent of the lines in the plays. The playwright had to know what stage of development each apprentice had reached. There were usually just two or three boys in the public plays (though more were available from choristers when a play was given at court or in a great family mansion). The boys’ memories were such that Shakespeare wrote shorter parts for them than for adult actors—an average of three hundred or so lines to the adults’ 650 or so lines per play. But when he had a spectacular boy like John Rice, he was able to write as big a role for him as that of Cleopatra (693 lines). Nothing could be more absurd than the idea of the Earl of Oxford writing a long woman’s part without knowing whether the troupe had a boy capable of performing it. Only Shakespeare, who knew and wrote for and acted with and coached John Rice, knew what he could do and how to pace him from play to play.
An acting company could not just pick up any boy off the street. The boy had to have a good voice and memory and diction—and preferably an ability to sing, dance, and perform on a musical instrument (like Lucius in Julius Caesar). After the Swiss traveler saw Julius Caesar, two of the adult actors and the play’s only two boys came out and danced the after-show jig. Where to get such talented boys, and how to train them? Of course, there were all-boy theatrical troupes in the chapels and schools, very popular and with their own professional writers—but some parents resented even those boys’ playing in secular dramas. The public theaters had much more trouble finding players for their female parts. Sometimes they could persuade a boy from the chapel or school to join them, or find a middle-class family with surplus boys willing to apprentice one—or even buy an apprentice from a troupe about to be dissolved. It was clearly hard finding and keeping boys of the requisite skills. (How many had to be dropped because the promise of talent proved illusory?)
Each boy had to be adopted as an apprentice, to live with an adult actor’s family. The boys were given board, food, and training, but no wages. The adult master had to swear to the good morals of his charge, to fend off Puritan attacks on the immorality of the theater. Shakespeare never had an apprentice of his own, since he did not have his family with him in London. When any boy’s apprenticeship ended, he could take advantage of his training by becoming a paid adult member of the troupe, perhaps a sharer in its property and profits. After marriage, he could acquire his own apprentice.
There are many signs of Shakespeare’s crafting roles for particular boys. In three plays of the late 1590s, A Midsummer Night’s Dream, Much Ado About Nothing, and As You Like It, he had one boy who was short and dark and another who was tall and fair. The contrast was so striking that Shakespeare made his lines play on it. He began with particular boys’ talents, and then wrote his scenes around them. He must have had a boy from Wales when he wrote I Henry IV, in which a woman speaks and sings Welsh. One of the experienced boys, in As You Like It, was good enough for Shakespeare to create his second- longest woman’s role for him—Rosalind (686 lines).
Very young apprentices were cast as little boys rather than as women, and they were given small parts to memorize—Macduff’s son in Macbeth (twenty-one lines), Lucius in Julius Caesar (thirty-four lines), Prince Edward in Richard III (fifty-one lines), and so on. As they matured in age and training, Shakespeare could give them larger roles as boys, like that of Prince Arthur in King John (120 lines) or the clever Moth in Love’s Labor’s Lost (116 lines). Only as they advanced farther into their teens could he trust them with important women’s roles, and with the doubling made necessary by the small number of boys for female roles. A boy recruited at age eleven or twelve had perhaps five years of training and performance before him.
Such experienced boys, a rare resource, had to be used with great economy. Lady Macbeth, as important as she is, has only one brief appearance (twenty lines) in the last two acts of the play. That is because John Rice was needed to double Lady Macduff (forty-five lines) in Act 3. It is poignant that Lady Macbeth, who was not in on the murder of Macduff’s wife, somehow learned of it before the sleepwalking scene when she says, “The Thane of Fife [Macduff] had a wife—where is she now?” (Act 5, Scene 1).
Cordelia in King Lear is absent from the play for an even longer time than Lady Macbeth. After the play’s first scene (forty-one lines), Cordelia is gone from the rest of Act 1 and all of Acts 2 and 3. She shows up in the last two acts to speak only forty-eight lines. This seems a very uneconomical use of a trained boy, until we notice that Cordelia exits the first scene well before the Fool shows up, and the Fool disappears before Cordelia returns. The Fool is an innocent “natural,” sexless and accidentally wise, unlike the “allowed fools” played by Robert Armin (Feste, Touchstone). Armin, it seems, played the “mad” Edgar, while a boy doubled Cordelia and the Fool.
Shakespeare was not a full-time writer without other responsibilities, like O’Neill or Williams. But what might look like a distraction for such authors—acting in his own and other people’s plays, coaching fellow players, helping manage the ownership of the troupe’s resources (including its two theaters, the Globe and Blackfriars)—was a strength for Shakespeare, since it made him a day-by-day observer of what the troupe could accomplish, actor by actor. The company was, after all, mounting plays with bewildering rapidity, studying, memorizing, and rehearsing in the morning and evening while performing in the afternoon. Without that experience, Shakespeare could not have written as he did. Lord Bacon or the Earl of Oxford, writing in their homes, could not have known such things. As Ivor Brown says, “Shakespeare was as much on and around a stage as in his study.”

Reference:
Garry Wills [2011]:  Shakespeare and Verdi in the Theater.  The New York Review of Books, LVIII (18):  34-36 (24 November – 7 December 2011).