Poetry is a form that needs strong meter. Poetry requires consistent word length, and words have clear word length restrictions according to different aphorisms. But in terms of leveling, the rhythm is very particular.

Fu is also a style, but what it requires is not the length of words, but the antithesis of writing. Every sentence of c is flat and even, rhyming and immortal, but it is strict with flat and even.

Where's the song? Poetry and songs are songs as long as they are accompanied by music.

Generally speaking, words are accompanied by fixed music according to the epigraph, and words must be songs. But poetry and fu don't necessarily have tunes.

To express a song better, it needs a certain rhythm, so the lyrics also need to be catchy, even, rhyming and easy to catchy.

So rhythm is the soul of the four.