One of the most famous quotes from the book, this line sums up the depth of Cathy's feelings for Heathcliff. She is not in love with him, she is him, they are not two people but one and the same. The line is often used in promotional material for television and film adaptations of the book such as this trailer for the ITV1 production of Wuthering Heights in the UK.
The same intoxicating approach was taken by Richard Wagner in his Tristan and Isolde, another highly-wrought and ill-fated romance, written less than ten years later:
You Tristan, I Isolde, no more Tristan!
You Isolde, I Tristan, no more Isolde!