Revelations and Realizations

[Lobelia]

Originally Posted by Bombadil

I believe that is Macbeth. Ironic it is too, for the witches say it about Macbeth.

Quite right! To be precise, "By the pricking of my thumbs/Something wicked this way comes."

As for JKR and the phrase, it wasn't even in the novel, only part of a choral piece in the film, based on the Shakespeare text.

Tolkien didn't even LIKE Shakespeare and he felt right cheated by Macbeth, especially the Birnam Wood business, which, as we know, was one of the reasons for the Ents, i.e. what if Birnam Wood really did come to Dunsinane? I am quite sure he would have been offended at the notion that he had a character quote from the Bard!