“Eye of newt, check,” muttered the First Witch, “and toe of frog, and what was the third thing?”

“Wool of sheep,” said the Second Witch confidently, but the Third Witch spoke over her: “Knees of bees and hair of the dog!”

By unspoken agreement, when the three met again, none of them spoke of the Birnam Wood Incident (and if Lady Macbeth was still sometimes seen licking her lips like the cat that caught the canary, well, surely that could be attributed to her own nature rather than the ill-advised addition of a cat’s meow to the witch’s brew).