And when it has got in; as one not finding what it seeks, whatever that may be, it wails and howls to issue forth again: and not content with stalking through the aisles, and gliding round and round the pillars, and tempting the deep organ, soars up to the roof, and strives to rend the rafters: then flings itself despairingly upon the stones below, and passes, muttering, into the vaults.