How we cite our quotes: All quotations are from The Two Towers.
Quote #4
WORMTONGUE: How? How can fire undo stone? What kind of device could bring down the wall?
Wormtongue cannot fathom the basic explosive science that Saruman has devised. To him, and to most of Middle-earth (maybe with the exception of the dwarves), Saruman's black powder is more like black magic he has conjured up. But it is merely an advancement in technology, one which will bring about the destruction of the world as we know it.
Quote #5
TREEBEARD: There is always smoke rising from Isengard these days… there was a time when Saruman would walk in my woods. But now he has a mind of metal and wheels. He no longer cares for growing things.
Saruman's iron works are the antithesis of thinks that grow. Growing things are living and provide life to the world and their ecosystems. But metal is cold and detached. It only serves to end lives.
Quote #6
THÉODEN: They will break upon this fortress like water on rock. Saruman's hordes will pillage and burn.
Théoden is using this natural imagery to illustrate how strong his defenses are. Helm's Deep has the permanence of a rock that cannot be altered. But maybe he'd rethink this analogy if he was about to happen to Isengard.