During the Warring States Period, Duke Wei of Qi neglected state affairs for the first three years of his reign, indulging in dissipation. One of his ministers, Chun Yukun, known for his good sense of humor, said to him: 'There is a big bird that has neither taken flight nor sung for three years.' The duke replied, 'Once that bird starts to fly and sing, it will astonish the world.' The duke thereupon devoted himself to his duties and built his state into a powerful one.
This idiom is used to indicate that a person may rise from obscurity and achieve greatness.