中古时代史学文本中的“事类”现象是指在对某段历史的叙述或评论中，引述历史上的其他情况，使具有一定时间距离的历史记忆交错、融合于同一史学文本之中。“属辞比事”的《春秋》之教提倡在提出某种主张之前，先系统地整理、解读古往今来的历史知识。司马迁以来的史家继承了《春秋》之教，将古代已经典范化的历史经验与近世的行事相参验，并在史书中设置古今参照的元素以传达史家的撰述意图与历史见解。

“事类”被史家广泛应用于历史评论之中。《史记》《汉书》《三国志》史论对普遍历史规律与政治观念的表达，一般会依托“前言往行”间接地传达；对人物、史事的历史定位则是通过呈现出某种特定的古今对应关系来实现。历史符号的选取与古今对应关系的建立都有通篇的布局和统一的标准，形成了“书法义例”。这种“书法义例”有三个要点：第一，与古人类比是一种褒美的方式，史家对所记述对象进行评价时用事会相当审慎。第二，受儒家二层史观的影响，史家会严格限制上古三代历史符号的使用。第三，史家主要利用“三代以下”的近古历史与其所记述的对象相参照，进行褒贬评断。在南朝成书的纪传体史书中，史论用事体例发生了新的变化：“事类”融入了总括性叙述；倾向于抹除征引和比较的痕迹；铺陈史事形成通史框架。这种变化后来为唐初所修的正史所继承。骈俪的文风、南朝重知识的风气都与史论用事体例的新变化有千丝万缕的联系，它们共同的底层逻辑是南朝社会的精英主义观念，对“文才”的过度推崇。晋唐间正史纪传论赞中主要发挥历史定位与褒贬评断作用的是“三代以下”的历史所构成的“近古参照系”，而从它们对上古三代历史的称引情况可以看出，“道谢三代”的历史观念并没有发生根本的转变，但围绕皇权的虚饰却越来越多。

纪传叙事中的“事类”的主要特征是作者的模糊性，它介于史家对事实的客观记述与史家的主观评断之间的叠加态，可归入“寓论断于序事”的范畴。中古史传叙事中“事类”文本的生成过程总体上可分为三个阶段：第一个阶段是历史行动者基于某种现实目的援引某些古代的历史记忆，这一过程中所产生的“事类”文本往往与历史进程本身难解难分；第二个阶段是以史官为主体的历史书写者对第一个阶段中产生的各类原始材料和传闻进行汇总，并加以选择、润色乃至虚构；第三个阶段则是系统性地隔代修史，形成纪传体、编年体的皇朝史。史家将原始材料中的“事类”呈现于史学文本中时会相当的审慎，会遵循当时的礼法与主流的历史观念。

帝纪书写中的用事与中古时期对皇帝权力秩序的理解紧密相关。王朝兴衰的“三代模式”对应于帝纪书写中的用事，就是要在创业君主即位之前通过载录含有古帝王符号的言辞以配齐王朝兴起所必需的天命和功德要素；在正式即位之后的本纪叙事中，史家要通过载录称引古代典范的“王言”来彰显皇帝在“法先王”，说明皇帝权力在正常地行使。从《三国志》开始，帝纪书写中的用事处理与禅让制相配套，以维护君臣秩序为宗旨，在创业之君本纪与末帝纪的用事中维护权臣与弱主之间尚存的君臣名分。这种在帝纪用事中维护君臣之礼的书法，在南北朝后期至唐初有松动的迹象，说明中古禅让制的实行从严肃变得愈发虚伪、形式化。

史书中的“事类”不仅仅是文学性的虚饰成分，它在史书中最重要的作用就是维持整体性历史框架的存在，让断代史保持“通古今之变”的功能。

Quotations and Allusions in historical texts of medieval times refer to the quotation of other historical situations in the narration or commentary of a certain period of history, so that historical memories with a certain time distance are intertwined and integrated into the same historical text. The study of the Spring and Autumn Annals requires that before putting forward a certain claim, historical materials from ancient to modern times should be systematically sorted out and interpreted, so that ancient and modern events go through a process of mutual reference. Since Sima Qian, historians have inherited the teaching of the Spring and Autumn Annals, and compared the exemplary historical experiences in ancient times with the practices of modern times, and set up a mechanism of ancient and modern reference in historical books to convey the historical views of historians.

Quotation is widely used in historical commentary by historians. The expression of general historical laws and political concepts in the historical theory of allusion, "Hanshu" and "San Guo Zhi" generally relies on "preface to the past" to convey indirectly; the historical positioning of figures and historical events is realized by presenting a specific correspondence between ancient and modern. The selection of historical symbols and the establishment of the correspondence between ancient and modern have a whole layout and unified standards, forming the "calligraphy examples". In the historical theory of the historical books written in the Southern Dynasty, the style of quotation has undergone new changes: quotation has been integrated into the general narrative; it tends to erase the traces of citation and comparison; historical events are spread out to form a general historical framework. The change of the style of quotation was later inherited by the official history compiled in the early Tang Dynasty. The elegant style of writing and the atmosphere of emphasis on knowledge in the Southern Dynasty are all intricately linked with the tendency of "Southernization" of the style of historical theory, but their common underlying logic is the elitist concept commonly existed in the Southern Dynasty, which over-praised and deified the talents of individuals. From the reference of the official history of the historical theory of the ancient three dynasties between Jin and Tang, we can see that the historical concept of today is not as good as that of the past has not changed fundamentally, but there are more and more pretentiousness around the imperial power.

The core feature of the use of allusions in historical narratives is the author's ambiguity, which lies in the overlapping state between the objective description of facts by historians and their subjective judgments. The generation process of allusion texts in medieval historical narratives can be generally divided into three stages: the first stage is when people use certain ancient historical memories orally and in writing for a certain practical purpose, and the allusion texts produced in this process are often difficult to distinguish from the historical process itself; The second stage is for writers and officials to summarize, select, polish, and even fabricate various raw materials and rumors generated in the first stage; The third stage is to systematically compile history, forming a chronological and chronological style of chronological history. Historians are very cautious when presenting the allusions from the original materials in historical texts, and will not violate the etiquette and historical concepts of the time.

The use of allusions in imperial chronicles is closely related to the understanding of the origin of imperial power in the medieval period. The "ancient model" of the rise of dynasties corresponds to the use of allusions in imperial chronicles, which means recording the words of ancient emperors to match the necessary elements of fate and merit for the rise of dynasties before the entrepreneurial monarch ascends to the throne; In the narrative of this chapter after the official accession to the throne, historians need to demonstrate the emperor's imitation of ancient wise rulers by recording and citing imperial edicts that exemplify ancient models, indicating that the emperor's power is being exercised normally and has not declined. Starting from the Records of the Three Kingdoms, the use of events in imperial records is aimed at maintaining the order of monarchs and subjects. However, there were signs of looseness in the maintenance of the etiquette of monarchs and subjects in the imperial records and allusions from the late Southern and Northern Dynasties to the early Tang Dynasty, indicating that the implementation of the ancient Zen abdication system had become more hypocritical and formalized from seriousness.

The use of allusions is not an exaggeration. Its most important role in historical books is to maintain the existence of a holistic historical framework, allowing the dynastic history to maintain its function of "connecting the past and present".