The definition of rare books and rare books has always been a controversial issue among edition appraisers. Teacher Song Xiaoxian once published a paper in 1987, pointing out: "Rare books are rare or precious books, and rare books are books with useful content, excellent proofreading and cultural relics, academic or artistic value."

In Li Zhizhong's view, "rare edition" is a precious, valuable and rare copy of western concepts and vocabulary. In fact, the concept of "rare edition" has replaced the meaning of "rare edition".

Books with a long history and handed down from generation to generation are naturally precious. Even if there are obvious words, it is a precious version, and there are examples in ancient and modern China and abroad. Originally, "Jane" is not equal to "goodness", and rare things are not necessarily good, but no one will treat precious things as dirt. This actually combines "Jane" and "goodness".