\'Guangling San\' is a famous piece of music written for the qin, a seven-stringed plucked instrument. It is said to date back to the Han dynasty. According to one commentator, the background to the piece is the assassination of Xia Lei by Nie Zheng in the Warring States Period, and the prevailing mood expressed is one of indignation. The quoted line is from the poem \'To Judge Han Chuo at Yangzhou\' by the Tang-dynasty poet Du Mu. R. F. Burton adds the following helpful note to his translation: "On the Bridge of Twenty Four in Yangzhou in former times two dozen beautiful ladies used to play their flutes." The whole poem reads "Mountains misty blue, mysterious, and distant water / South of the River, as Autumn ends, the grass has not yet withered / Above the Bridge of Twenty Four the moon dispels the night / Where is that Adonis giving lessons on his flute?" See Plaintains in the Rain (London: Wellsweep, 1990)