From Xin Qiji's
辛弃疾 Southern Song ci
《菩萨蛮·书江西造口壁》:
青山遮不住,
毕竟东流去. (The green mountains cannot hold it back; after all, the river flows east.) Written on a wall at Zaokou in Jiangxi while mourning the Song court's retreat - the flowing river became a symbol of irreversible history.