《文心雕龙·乐府》
但读了曹操的《苦寒行》、曹丕的《燕歌行》等作品，觉得里边无论叙述宴饮或哀叹出征，内容都不免过分放纵，句句离不开悲哀的情绪；虽然直接继承汉代乐府诗，可是比之《韶乐》、《大夏》等古乐却差的远了。
观其北上众引，《秋风》列篇，或述酣宴，或伤羁戍，志不出于杂荡，辞不离于哀思。虽三调之正声，实《韶》、《夏》之郑曲也。
However, after reading Cao Cao's "Bitter Cold" and Cao Pi's "Yan Ge Xing", I felt that the content was too indulgent, whether describing banquets or expressing grief about going on expeditions, and the sentences were all filled with grief; although it directly inherited the poems of the Han Dynasty Yuefu, it was far behind ancient music such as "Shaoyue" and "Daxia".