'There is a big bird which has neither taken wing nor sung for three years

'There is a big bird which has neither taken wing nor sung for three years.' The duke answered, 'Once that bird starts to fly and sing, it will astonish（使惊讶） the world.' The duke thereupon（于是，随即） devoted himself to his duties and built his state up into a powerful one.This idiom is used to indicate that a person may rise from obscurity（朦胧，阴暗） and achieve greatness.