Hallucinations of Shakespeare

When English tourists abroad are accosted by foreigners on trains it is now more likely to be about Manchester United or Downton Abbey. According to the writer Maurice Baring, in his time it was often about Shakespeare, as in this intriguing account in his Lost Lectures (London, 1932):

Over and over again it has been my fortune to be told about English literature by foreign high-brows in trains, and to be initiated in the secrets of the literature of my country. I once met a Serbian professor who told me that he had written a book about Shakespeare. He spoke French (not Shakespeare—the Serb). Shakespeare was a well known case, he said, of self-hallucination. He knew, because he was a mind doctor. Hamlet was a well-known case of a man who thinks he sees ghosts.
“But”, I said, “the other people in the play saw the ghost.” “They caught his infection,” he said.
“But they saw it first,” I objected.
“It was Suggestion,” he said; “it often happens. The infection comes from the brain of the man who thinks he sees a ghost before he has seen the ghost, and his coming hallucination infects other brains. Shakespeare hallucinated, or he could not have described the case so accurately. All his characters hallucinated—Macbeth, King Lear, Brutus (he saw a ghost).”
I said enough things had happened to King Lear to make him go mad. “Not in that way,” he said. “Ophelia is mad; Lady Macbeth is mad; Othello is mad; Shylock is mad; Timon of Athens is very mad; Antonio is mad; Romeo is mad. The cases are all accurately described by one who has the illness himself.”
“Was Falstaff mad?” I asked.
“Falstaff,” said the doctor, “is a case of what we call metaphenomania.
He was a metaphenomaniac; he could not help altering facts and changing the facets of appearances.”
“What we call a liar?” I suggested.
The doctor said that was an unscientific way of putting it, but it was true. Then he got out.