Why is the dragon dancing sad?

The sadness of the dragon dancing is due to the bleak sadness of the flute. Dragon dancing originated from the article "Red Cliff Fu". In the second section, when describing Xiao Sheng, Xiao Sheng's desolation and sadness were described by dancing the hidden dumpling in the secluded valley and weeping for the widow in the lonely boat, meaning that even though the hidden dragon dancing in the abyss made the widow in the lonely boat weep.