Which two poets does Su Xin refer to?

Su Xin is the collective name of Su Shi in the Northern Song Dynasty and Xin Qiji in the Southern Song Dynasty. Both of them are representatives of bold poets. Gao Youyi's preface to Chen Qinian's Lake and Sea Building introduces Gu Xian in three words: "Song Ci is the most prosperous, with different styles. Su and Xin are bold, Qin and Liu are charming and romantic, and they are classified into different categories. " Since the "Huajian School" in the late Tang Dynasty, the words are graceful and authentic, and the poems are charming and almost fixed.

When Su Shi arrived, he created the bold school with bold and vigorous brushwork, expanded the scope of the theme of Ci, opened up the field of expression of Ci, broke the barrier that Ci was a colorful theme and liberated the style of Ci.

Qing Zhou Ji's Preface to Selected Poems of Song Sijia: "Su Xin also said that Dongpo's natural taste is unique, which has almost become a unique thought ... Jia Xuan is immersed in happiness and has a way to follow." Chen Qingting's "White Jade Zhai Thorn" Volume 1: "Su Xin also said that they are by no means similar: they are courageous, but Su Xin is not as good as Xin; The gas is so high that Xin Zhui can't reach Su Yuan. "