I don't think the understanding of the word melon is watermelon. If it is a watermelon, will it be planted under the yellow platform? Besides, only one or two watermelon seedlings can be picked, not as many as three or four. Huangtai, I think it's an earthen terrace, a bit like a loess wall. The seedlings grow against the loess wall. I thought that Li Xian used the word "Huangtai" here, not vines or anything else, which means that he secretly pointed to the emperor and queen. Huangtai stands for power, which means that the princes grew up around the emperor and queen and were brought up by them. When the melon is ripe, the seeds are separated, indicating that there are many seeds when the melon is ripe, and the seeds are the same. This sentence ends. The son here alludes to the prince, and the core of the two sentences is here. Later, I turned to picking melons. I picked melons here, not seeds! You can't pick seeds. But why say the first two sentences? I think it is mainly to let readers deeply understand the inner meaning of poetry. Picking melons is after they are ripe, not when they are not ripe, so this is not what we now understand as "keeping seeds" for melons. The last four sentences have no deep meaning, just a process of picking melons. If they are related to politics at that time, I think they are as follows:
First, Li Hong, the eldest son of Wu Zetian, was made a prince, while Jong Li, the former prince, was abolished. Li was born by Wu Zetian, so he was the first to pick melons, so he removed the position of the prince and was replaced by his eldest son Li Hong. This first step achieved the goal of making the prince become Wu Zetian's own. In this way, Wu Zetian's rights are even greater.
Second, he poisoned his eldest son, Li Hong, and replaced Li Xian as the prince. In this way, one of Wu Zetian's four biological sons was missing. At this time, Wu Zetian's own son has passed away. If Li Xian is abolished, only the last two sons will be left, so it is said that the melon is thin again.
It's better to choose three, but if I sit in the position of Prince Li Xian, someone will take over. Therefore, it is ok to say yes, but it is "return". You can barely regenerate a prince. At this time, it is already the third son of Wu Zetian.
If you let your third biological son be a prince and then depose him, you can only do it again, but do it again, that is Wu Zetian's fourth son, the last one! Excuse me, do you want to continue to choose this? I'm afraid that after Wu Zetian picked this melon, none of his four biological sons were left. What should Wu Zetian do? This fourth melon is the last one, attached to the vine. All you have to do is shake off the vines and take them away, and then there's nothing left!
This is an exhortation poem, which strongly points out that Wu Zetian frequently deposed the Prince, showing Li Xian's dissatisfaction with this matter and her concern for herself. Even so, it did not stop Wu Zetian from abolishing the prince. Three of Wu Zetian's four sons are princes, and the fourth son Li Dan was directly promoted to the throne of the emperor by her.
But what Li Xian didn't expect at first was that Wu Zetian was waiting for the fourth one! Because, only after picking the fourth melon can she really come out and become a real emperor!