What is a joke and how difficult is it to practice? What article is it about?

There were five college students in the dynasty, and I want to recall four; Six ministers, I have to recall three. Look at these seven people. They are not from the temple, the pillars of the imperial court, or my children's in-laws. They are rotten, and my heart is broken! My ancestors handed the country into my hands, but this is the result. I am sad. I am ashamed of my country, my ancestors and heaven and earth. I can't wait to leave myself! And you, although standing on the dry shore, are you that clean? I know some of you are more corrupt than these seven people! I advise you to turn out your heart, lungs and intestines, bask in the sun and wash up! When I first acceded to the throne, I thought that Yan Bai was the greatest enemy of the imperial court. When I destroyed Yan Bai, I thought that Wu Sangui was the greatest enemy, so I attracted Wu Sangui. Taiwan Province Province became a pain in the heart of the Qing Dynasty. Ah, I accepted Taiwan Province Province and Gedan, which became a pain in Qing's heart. I am more and more clear now that the trouble of purity is not outside, but in the imperial court, where the Qing palace is dry! Among my flesh-and-blood princes and ministers, if we are a little rotten here, the Great Qing Dynasty will be rotten. If you are all rotten, all parts of the Qing Dynasty will rise up, and none of us will come to a good end! Think about it. Zhu Youjian, Emperor Chongzhen, hanged himself in Jingshan Park for only a few years. Forget it! That old crooked neck tree is still standing behind the palace, staring at you every day! I haven't slept for three days and nights. I always want to say something to you, but I have to do it. Think about it, there are only four words. These four words are easy to say, but how difficult is it to practice? These four words were dug out of my heart, from the sea of blood. Remember, starting from today, this hall will be changed into an aboveboard hall. Take a good look ... oh, you all look up, take a good look, think about yourself and show it to me for half an hour.