"Thou, from whose unseen presence the leaves dead
Are driven, like ghosts from an enchanter fleeing..."
See in text (Ode to the West Wind)
The last two words in each of these two lines are reversed. The normal syntax would be: "the dead leaves are driven like ghosts fleeing from an enchanter." By reversing the normal order, Shelley imitates the pell-mell, helter-skelter flight of the stricken leaves. Those in back are tumbled into the front by the wild wind, and other leaves behind in the rout will be blown in front of them.