Nevertheless, the passion between the two lovers remains rooted in their hearts, impervious to external contingencies. The text consistently treats the love between Catherine and Heathcliff as an incontestable fact of nature. Nothing can alter or lessen it, and the lovers know this. Heathcliff and Catherine know that no matter how they hurt each other, they can be sure of never losing their shared passion and ultimate mutual loyalty. Catherine can decide to marry Edgar, certain that this outward act will have no effect on her and Heathcliff’s inner feelings for one another. Similarly, it is in the knowledge of their passion’s durability that Heathcliff later undertakes his cruel revenge.