待到长虹贯日花飞尽
[dài dào zhăng hóng guàn rì huā fēi jĭn]
Translating into 'Waiting until the rainbow crosses the sun and all the flowers fly', it shows a poetic scene where one waits for an ideal day or state while witnessing the fading beauty around. It's also used to imply anticipation for great achievements or moments under hardships or after a long process.