As different as a moonbeam from lightning, or frost from fire

 ‘This is nothing,’ cried she; ‘I was only going to say that heaven did not seem to be my home; and I broke my heart with weeping to come back to earth; and the angels were so angry that they flung me out, into the middle of the heath on the top of Wuthering Heights; where I woke sobbing for joy. That will do to explain my secret, as well as the other. I've no more business to marry Edgar Linton than I have to be in heaven; and if the wicked man in there had not brought Heathcliff so low, I should have thought of it. It would degrade me to marry Heathcliff, now; so he shall never know how I love him; and that, not because he's handsome, Nelly, but because he's more myself than I am.  What ever our souls are made of, his and mine are the same, and Linton's is as different as a moonbeam from lightning, or frost from fire.'

Ere this speech ended I became sensible of Heathcliff's presence. Having noticed a slight movement, I turned my head, and saw him rise from the bench, and steal out, noiselessly.  He had listened till he heard Catherine say it would degrade her to marry him, and then he staid to hear no farther.

. . . "I cannot express it; but surely you and every body have a notion that there is, or should be, an existence of yours beyond you.  What were the use of my creation if I were entirely contained here? My great miseries in this world have been Heathcliff's miseries, and I watched and felt each from the beginning;  my great thought in living is himself.  If all else perished, and he remained, I should still continue to be; and if he were annihilated, the Universe would turn to a mighty stranger.  I should not seem a part of it.  My love for Linton is like the foliage in the woods. Time will change it, I'm well aware, as winter changes the trees -- my love for Heathcliff resembles the eternal rocks beneath -- a source of little visible delight, but necessary.  Nelly, I am Heathcliff -- he's always, always in my mind -- not as a pleasure, any more than I am always a pleasure to myself -- but, as my own being -- so, don't talk of our separation again -- it is impracticable; and --'

She paused and hid her face in the folds of my gown; but I jerked it forcibly away.  I was out of patience with her folly!

from Wuthering Heights, by Emily Bronte.