Ai (哀) and diao (吊) essays were written in ancient times to express mourning for someone who had died a natural death or from an extreme misfortune. Ai, or an essay of mourning, was written to express grief or compassion. It was originally written for someone who died young; later, it was written to mourn a person’s miserable life or unfortunate encounters. Diao, or an essay of memory, was intended to express one’s deep affection for a long-deceased person or to offer his sincere condolences to the fatal misfortune suffered by a particular country or an individual. An essay of mourning was usually written for a recently deceased person, whereas an essay of memory showed one’s abiding love for someone who died long ago. Stylistically, there is much resemblance between these two types of writing. They were like today’s condolence speeches delivered at funerals, and some may be characterized as mourning or nostalgic lyrical essays. As Liu Xie (465?-520) put it in his literary critique The Literary Mind and the Carving of Dragons, ai, or an essay of mourning, expresses sorrow for the deceased person’s yet unaccomplished merits, so it need not be excessively rhetorical in style. Diao, or an essay of memory, on the other hand, often shows one’s love for someone who died long ago, so it may contain an evaluation of his life tinged with sentimental attachment. Liu’s views still influence prose writing today.

Ai, an essay of mourning, written in a pompous style, beautiful as it may sound, will not really arouse a sense of grief among its readers. Only an essay which expresses one’s deeply felt emotions and moves readers to tears can be regarded as a truly remarkable essay. (Liu Xie: The Literary Mind and the Carving of Dragons)

Although the meaning of diao, or an essay of memory can be traced a long way back, it was much later that an essay of memory became excessively rhetorical in style. If such an essay is written in a flowery style and drags on, it would look more like fu or rhapsodic prose. In writing an essay of memory, one should focus on a key message and explains its relevance, extol virtue and warn against errors, distinguish right from wrong and make evaluation accordingly, and express grief without distracting from the core message. These are rules to be observed in writing essays of memory. (Liu Xie: The Literary Mind and the Carving of Dragons)