Lust, Caution is a novel published by Huacheng Publishing House 1997. It was written by Zhang Ailing 1950, and it was published in her subset Dissatisfaction 30 years later.
The latter sentence has been criticized by many people. In fact, this sentence is not Zhang Ailing's original. The real creator is the German poet Goethe. His original words were: "The ocean is the largest in the world, the sky is bigger than the ocean, the human heart is bigger than the sky, and the passage to a woman's heart is the vagina."
Here, "vagina" refers to a medium, not just sexual intercourse itself. Vagina is just a door to open the atrium here, which represents an initial "open door" acceptance for him. After being allowed in, since we are already a person with a common space. Of course, you can share more until you fully share your heart. Enjoy family happiness.