2 questions about one sentence 【"Oh!  captive, bound, and double-ironed," cried the phantom, "not to know, that ages of incessant labour, by immortal creatures, for this earth must pass into eternity before the good of which it is susceptible is all developed. "】 1. what does "immortal creature" here mean? 2. in "the good of which", what does this "which" indicate? the earth's good? or the immortal creatures' good?