Of all Shakespeare’s plays, perhaps none is stranger than “Macbeth”— a parable on power rife with supernatural elements. But according to texts from the 11th century, this tragedy has its roots in reality. What’s more, other accounts mention witches, prophecies, and arboreal armies. Which raises the question: just how much of Shakespeare’s strange story is true? Benjamin Hudson investigates. Lesson by Benjamin Hudson, directed by Sarah Saidan.