Ellen describes Catherine Earnshaw Linton's corpse as peaceful:
"Her brow smooth, her lids closed, her lips wearing the expression of a smile; no angel in heaven could be more beautiful than she appeared. "
Catherine had just suffered the torment of having a baby right after the mental torment of longing for Heathcliff and her life of freedom and love before her oppressive boring marriage to Edgar. Her suffering was over and her soul could find eternal happiness haunting the wild moors of her childhood.
When Ellen finds Heathcliff dead in his bed, soaked in rain from the open window she was startled by the eeriness of his corpse:
". . .Mr. Heathcliff was there--laid on his back. His eyes met mine so keen and fierce, I started, and then he seemed to smile. . .I could not think him dead: but his face and throat were washed with rain: the bed-clothes dripped, and he was perfectly still.. .I tried to close his eyes: to extinguish, if possible, that frightful, life-like gaze of exultation, before anyone else beheld it."
Did Catherine's ghost come for him finally? If he died while smiling in exultation, he must have been experiencing something that made his soul leap from his body and his heart suddenly stop.
I find it interesting and strangely comforting how people dealt with death during the 19th century when could people die at any time of life because of lack of the vaccines and medical advancements we take for granted now. People still mourned the deaths of their loved ones, but death didn't come as a complete shock like it seems to now unless the departed was extremely advanced in age. It was so sad when Heathcliff sneaked into the house to put his hair in Catherine's locket, except for the fact that he tossed Edgar's lock of hair on the floor to make room for his own. That was pretty rude.