What is the greatest poem in history (ancient and modern, Chinese and foreign)?

The world has recognized Qu Yuan's Nine Songs.

"Nine Songs" was adapted or processed by Qu Yuan, a Chu man in the Warring States Period, according to folk music songs offering sacrifices to gods. * * * Eleven articles: Emperor Taiyi, Prince in the Cloud, Lady Xiang, Little Siming, Hebo, National Mourning, Ritual Soul. A "national mourning", mourning and praising the soldiers who died for Chu; Most of the chapters describe the attachment between immortals, showing deep yearning or harm without desire or desire. Wang Yi said that Qu Yuan did it when he was exiled to Jiangnan. At that time, Qu Yuan was "full of worries and worries", so he wrote music and songs to worship the gods to express his thoughts and feelings.