關於古今關係的認識，是中國古代歷史理論的一個重要方面。魏晉隋唐間的史學家、思想家和政治家對古今關係的認識有了新的發展：一是人們對於歷史上的“古”史書記載中的“古”有了初步的區分；二是人們對於“居今識古”和路徑和意義有了更明確的認識，三“疑古”和“釋古”的發展推進了歷史認識的深入，四是古今關係的展分是認識與政治實踐的聯繫，人們認識到致治之要務在當今的道理，反映了對古今關係的認識更加趨於合理性。

The knowledge about the relations between the past and the present was very important in the theory of Chinese ancient history. The historians, ideologists and politicians from the Wei and Jin to the Sui and Tang Dynasties had the latest developments in the knowledge about the relations between the past and the present. First, people primarily knew the antiquity in historical records. Second, people had definite knowledge of Residing Now to Know Past. Third, people added the understanding of history with the development of doubting antiquity and interpreting antiquity. Fourth, people knew that nowadays is pivotal in political practices, which reflected the knowledge about the relations between the past and the present trending to be reasonable.