Was there a prophecy that the forest would move against Saruman?
I'm sure I read somewhere that there was a prophecy that Isengard would stand until the forest moved against it, or something to that effect. However, I cannot figure out where I got that from.
I thought it was actually the reason why he intentionally destroyed the forest. He was trying to prevent the prophecy while actually causing it.
Yet, I cannot find any proof of this. Did I just imagine this?
In a letter, he wrote of his "bitter disappointment and disgust from schooldays of the shabby use made in Shakespeare [in Macbeth] of the coming of 'Great Birnam wood to high Dunsinane hill'". He attributed his creation of a world containing tree-giants or Ents to this reaction, writing "I longed to devise a setting in which the trees might really march to war."