Mr. Jiang has used up his literary talent-At one's wit's end
During the period of Southern and Northern Dynasties (420-589), there was a man of letters named Jiang Yan, whose father died young. Little Jiang Yan was strenuous and diligent, capable of writing beautiful poems and essays at his early age. He, who was thought highly of by those men of letters of that time, was called Mr. Jiang.
However, the great fame and high position prevent him from go on making progress. His articles and poems written later were not a match to his earlier ones. People said that he was at his wit's end.