Strictly speaking, the superstition states that actors must not utter the name Macbeth in a theatre. If they do, the show currently on at that theatre will soon close. The only way to avoid the curse is to leave the theatre, walk around it three times, spit over your left shoulder and curse. Others believe that merely spinning around on the spot three times and spitting will suffice, while another way to undo the toil and trouble of the curse is by reciting lines from other Shakespeare plays.
It is usual, therefore, for theatrical folk to refer to ‘the Scottish play’, rather than name it. The most popular explanation is that Shakespeare used real spells revealed by real witches when writing the play.
The witches were so angry at having their secrets revealed, it is claimed, that they cursed the play and its name. However, there is little evidence for the superstition before the later 18th century, so its true origins are a mystery.
Answered by one of our Q&A experts, historian and author Rupert Matthews