The Old Globe is staging two plays about monarchs gone mad: Shakespeare’s King Lear and Alan Bennett’s Madness of George III. Lear’s is self-inflicted. A seemingly simple test of love has a “butterfly effect.” Families fall, nature almost unravels, and the king’s insanity scourges his being. They say the Lord gives us only suffering we can handle. Lear’s epic plight questions that ­claim.

Great Britain’s King George III (1738–1820) ruled when the 13 colonies won their independence (he called America “the place we mustn’t mention”). In 1788, he experienced severe abdominal pain and aching skin that made linen feel like a hair shirt; he shivered, his urine turned blue, and he babbled nonstop, at one point for nine straight hours. Many in his court refused to believe he was ill. After all, when it came to eccentricity, monarchs had a King’s ­X.

Bennett’s play walks hand-in-hand with King Lear, but with a difference: Lear’s madness was psychological. George showed all the symptoms of insanity, but his madness was physical (resulting, many say, from a “porphyria,” a blood disease); he was actually a sane mind in an insane body. “I have always been myself,” he says, “even when I was ­ill.”

George’s mania prompted the Regency Crisis of 1788. What to do? Keep the king as a blithering figurehead? Declare him unfit? But then what? His absence could topple a government and the majority his patronage created. Behind the scenes, Tories and Whigs — among them the Prince of Wales, William Pitt, and Richard Brinsley Sheridan (author of The School for Scandal) — jockey for power. “The King’s illness,” says Charles James Fox, “is a civil ­death.”

A battery of doctors tries to heal the king, and 18th-century medicine looks as primitive as ours will two centuries hence (you can hear Bones of Star Trek shouting, “It’s medieval!”). One doctor’s obsessed with the pulse, another with stool samples, a third advocates “blistering”: to let foul humors escape, he applies heated glass containers to the king’s scalp. They actually mean well, though their methods result in Inquisition-strength torture. Bennett italicizes that point: while face down as if on a rack, the king shouts, “I’m the Lord’s ­anointed!”

Ralph Funicello’s set could host a royal farce: eight mirrored double doors semicircle the playing space. They make for courtly entrances (along with puffy wigs, Deirdre Clancy’s costumes include numerous red coats with gold trimmings) or farcical escapes. The director creates flurries of disorder onstage, but none compare to the ­king’s.

George III was in many ways King Lear’s opposite. He loved to go among the people and knew the names and genealogies of seemingly thousands. In Madness he experiences a Lear-like fall. If Great Britain were a single declarative sentence, he was the “subject and the verb.” Now he’s “the ­object.”

Miles Anderson plays the king like an inverted iceberg: deep, deep down, at the tip, the man is sane. Everything else becomes a vast burden that Anderson, in an exceptional performance, somehow overcomes (for the time being, though; George III died blind and mad in ­1820).

The king recovers, in part, thanks to Willis, a preacher-turned-psychotherapist, who lords it over the king (“you are not fit to govern others,” Willis tells him, “and until you do, I shall govern ­you”).

Under Adrian Noble’s inventive direction, the Old Globe’s summer festival intersects in Willis. His authoritarian tactics recall Petruchio’s in The Taming of the Shrew. And Robert Foxworth plays Willis — and King Lear (which Willis, in a line dripping with irony, says he never read). Foxworth gives the man an unwavering, almost mystical sanity, the exact opposite of his ­Lear.

Andrew Dahl’s a kick as the Prince of Wales, a corpulent idler who strikes poses with his cane and dreams of kingship (“My father ruled me like he did the Bostonians,” he chortles, “and now this is my tea party”). Emily Swallow gives the queen a loving patience (another irony: since Swallow also plays mercurial Kate in Shrew). A flask never far from his lips, Jay Whittaker’s William Pitt exudes an almost mad ­ferocity.

Bruce Turk, Adrian Sparks, and Joseph Marcell make the attending physicians an absurdist nightmare — as self-important as they are harebrained. But like the king, they only seem ­mad.

In the original script, Bennett has a modern doctor announce that the king suffered from porphyria. The disease has been a catch-all for unaccountable illnesses in, among others, Mary Queen of Scots, Vlad the Impaler, Vincent Van Gogh, and werewolves. The director cut the brief scene, most likely because historians now believe George III suffered from severe bipolar disorder and that all attempts to cure him, except Willis’s, exacerbated the ­condition. ■

The Madness of George III by Alan Bennett
Old Globe Theatre, Lowell Davies Festival Theatre, Balboa Park
Directed by Adrian Noble; cast: Miles Anderson, Emily Swallow, Michael Stewart Allen, Charles Janasz, Jay Whittaker, Robert Foxworth, Andrew Dahl, Donald Carrier, Grayson DeJesus, Bruce Turk, Adrian Sparks, Craig Dudley, Joseph Marcell, Shirine Babb; scenic design, Ralph Funicello; costumes, Deirdre Clancy; lighting, Alan Burrett; sound, Christopher R. Walker
Playing through September 24; runs in repertory with King Lear and The Taming of the Shrew. 619-234-5623.