What does it mean to beg for melons under the low wall in summer?

Asking for a melon in summer means wanting a cucumber in summer, but accidentally tripping over a very low wall. This is an unfair fate. You can get the melon when you cross the low wall, but you can't even get through such a small difficulty. Describe the author's sigh and regret for the untimely life, unreasonable fate and unfair fate.

This sentence comes from Lv Mengzheng's Cold Kiln Fu, which lists the fate and hardships of many celebrities from ancient times to the present, and makes sense with facts.

Article creation background:

Lv Mengzheng entered the phase three times and served as the teacher of the Prince. At that time, the Prince (later Song Zhenzong) was young and arrogant, and no one dared to teach the Prince a lesson to his face. Lv Mengzheng decided to write an article to warn the prince. So I wrote this "Broken Kiln Fu".

Although the content of this article is short, it contains infinite wisdom, and the clever prince understands the truth at once. It is said that after reading this article, the prince changed his normal state and often asked for advice modestly.

About Lv Mengzheng:

Lv Mengzheng, the prime minister of the Song Dynasty, was abandoned by his father when he was young and suffered from poverty and cold in this world. He once lived in a cold kiln with his mother and lived by begging. After studying hard, I finally became the best official. From being despised to being admired, I deeply felt that heaven was impermanent and human feelings were warm and cold, pretending to be a "broken kiln woman." Although there are views in the article that are too resigned to fate, there are indeed many inspiring words. I advise you to read "Broken Kiln Fu" often, and never look down on others.