没有阳光的雨反射不出彩虹
[méi yŏu yáng guāng de yŭ făn shè bù chū căi hóng]
'Sunlight-less rain cannot reflect a rainbow.' It uses a poetic description based on natural phenomena that highlights that certain beauty or wonder requires the combination of specific elements (rain and sunshine) coming together - hinting that perfect moments depend on particular conditions aligning perfectly.