As for the rhythm of rhythmic poetry, it is said that there is such a formula: "One, three, and five are irrelevant, but two, four, and six are clear." This refers to the seven rhythms (including the seven uniques). This means that the first, third, and fifth characters can be in any order, but the second, fourth, and sixth characters must be in clear order. As for the seventh character, the requirements are naturally clear. If we are talking about five-character rhymed poetry, it should be "No matter one or three, two or four are clear."
This formula is useful for beginners to learn rhymed poetry, because it is simple and clear. However, its analysis of the problem is comprehensive, so it can easily lead to misunderstandings. This has a great impact. Since it is not comprehensive, it cannot but be appropriately criticized.
Let me first say that the sentence "ignore one, three or five" is not comprehensive. In the five-character pattern "平平廄廄平", the first character cannot be ignored. In the seven-character pattern "廻仄平平廄廄平", the third character cannot be ignored, otherwise it will be a solitary character. In the specific format of the five-character "平平廄平廄", the first character cannot be ignored; similarly, in the specific format of the seven-character "任仄平廄平廄", the third character cannot be ignored either. The above is about the first character of the Five Characters and the third character of the Seven Characters, which cannot be ignored under certain circumstances. As for the third word of five words and the fifth word of seven words, under normal circumstances, the principle is "Lun".
In short, a seven-character sentence with oblique legs can have three words, and a sentence with flat legs can only have two words. A five-character, square-legged sentence can have two characters, while a flat-legged sentence can only have one character. It is wrong to say "I don't care about one, three or five".
Besides, the sentence "two, four, and six are distinct" is not comprehensive. The second word of the Five Characters, "明明", is correct, and the second and fourth words of the Seven Characters, "明明", are correct. As for the fourth word of the Five Characters and the sixth word of the Seven Words, they are not necessarily "Mingming". According to the specific format "平平廄平廄", the sixth character is not necessarily "clear". Another example is the format of "廄仄平廄" which can be changed to "廄仄 平廄廄" by adding a flat tone in the third word of the couplet. The seven words can be deduced from this. "Two, four, and six are distinct" is not entirely correct.
——Excerpt from Wang Li's "Poetic Rhythm"