Literature Reference: 黄墟既杳杳，玄化亦茫茫。 —— 《从事淮南府过亡友杨校书旧厅感念愀然》 The past is distant and obscure, and the profound transformation is vast and boundless. Source from 'Engaging in Mourning at the Old Hall of My Late Friend Yang the Scholar in Huainan Prefecture'.