The "Before the Red Cliff Rhapsody" was a poem written by the poet Su Shi, also known as Su Dongbo, in the the Song Dynasty. It was a pair of poems, the other one being the "After the Red Cliff Rhapsody". Both of these poems are famous both for their rich language, as well as covering most of the major important aspects of Chinese culture of the time.
The poem was written by Su Dongbo in one of his many periods of exile. Su Dongpo, who was a high ranking political official, ran afoul of the Imperial Court, and was sent to Hunan Province, where he spent his exile studying Buddhism and Taoism and writing poetry. The poem is written in the fu form, which is translated as "rhapsody" or "prose poetry". This form used rich, evocative language, interspersed with rhyming lines. (Although the lines don't neccesarily rhyme in the modern Chinese language).
The plot of the poem is simple: Su and two or three friends go out on a boat on the Yangtze River, where they play music and drink wine. One of his friends plays a sad tune on the flute, prompting Su to ask what is disturbing him. The flute player discusses the Battle of the Red Cliffs, a famous battle described in the Romance of the Three Kingdoms, and how the men who fought it, famous heros of the time, are now dead for hundreds of years; and how simple people like themselves were even more given to being adrift on the currents of time.
At this point, Su describes in philosophical language taken from Taoism and Buddhism, how while from one point of view everything is changing, from another viewpoint, everything is changeless. There fears being relieved, the boats occupants fall asleep, drifting on the river.
The poem is famous for combining Chinese history and philosophy into a rich examination of life, all within a few hundred characters. There are many philosophical and historical questions still to be settled from the poem, many of which are probably left to subjective judgement.