Literature Reference: 曳履忘年旧，弹冠久要情。—— 李德裕《重过列子庙追感顷年自淮服与居守王仆射同题名于庙壁仆射已为御史余尚布衣自后俱列紫垣继游内署两为夏官之代复联左揆之荣荷宠多同感涕何极因书四韵奉寄》 Dragging my shoes, I forget the past years; dusting off my hat, I cherish long-held friendships. Source from Li Deyu's poem.