Wen Yiduo advocates that poetry has "three beauties". What is "three beauties"?

Mr Wen Yiduo is an important poet, scholar and soldier in the history of modern literature in China. He not only devoted himself to the exploration of the artistic beauty of new poetry, but also put forward a new metrical poetry theory of "three beauties" of music, painting and architecture, and also worked hard to create and write many beautiful poems. His theory of new metrical poetry is called the cornerstone of modern poetics by later generations and has far-reaching influence.