I checked Feng Zikai’s translation. On page 196 of the first volume, it says that it is an ancient saying and only has these two sentences. There is no whole poem. The whole paragraph is below. This is what LZ said. The last sentence, "Aoi-hime" in Chapter 9 of "The Tale of Genji":
It is said that Aoi-hime was possessed by a spirit, and her illness worsened and she was very painful. People in the world spread the legend that this was the life of Concubine Rokujo and her daughter. The ghost of my late father, the minister, is causing trouble. When Concubine Rokujo heard about this, she was filled with thoughts. She reasoned: "I only regret myself and don't resent others. But if I am too melancholy, my soul will leave the body and float out, causing mischief for others. This is inevitable." In recent years, she has been sad and worried about various things, but I have never been more heartbroken than this time. Ever since the day when I was fighting for a parking space, I was despised and suffered great humiliation. I have been filled with sadness and regret, and my mind is often wandering and unable to calm down. Therefore, whenever I am confused and fall into a dream, my mind wanders to a certain bridal chamber in the Qing Palace, as if it is Kui Ji's home, and I am entangled with this person. Her sexual behavior at this time was completely different from when she was awake: fierce and violent, only attacking this person. This is a frequent occurrence recently. She often thought: "Oh, I'm so ashamed! Could it be that my soul really left my body and went to Kui Ji?" She felt that it was not coming from the original intention, which was very strange. She thought again: "Everyone in the world will gossip about trivial matters, not to mention my behavior, which is a good way to teach others to spread their bad reputation." She lamented her reputation and thought repeatedly: "What if it was a dead person?" It is common in the world for people to have lingering resentments and cause trouble. But even if others do this, I still think it is a serious sin and abominable. What’s more, for me to be given such a bad name while I’m alive is really a sin committed in my past life! It's all because I fell in love with that thin lover. From now on, I will never think about him again." Even so, as the old saying goes: "I don't think about it anymore.
Why not even think about it? ”