The « Jingji zhi » of the Suishu mentions a book dedicated to the Shijing 詩經 which is attributed to a certain Lu Ji 陸機 and entitled Maoshi Caomu Chongyu shu erjuan 毛詩草木蟲魚疏二卷 [A subcommentary in two rolls on plants, trees, insects and fish in the Mao Odes]. Unfortunately, Lu Ji is not the famous author of the « Wenfu », and the time of composition of the book has proved impossible to tell. But fortunately enough, it has come down to us, even expanded by Mao Jin (1599-1659). The commentary is unique in both its form and purpose: it is a glossary on elements of nature mentioned in poems. However, the information thus gathered is never used to explain the meaning of the poem. I propose to present a set of documents: excerpts from this commentary, a few poems and a selection of early medieval textual material. I will argue that this work’s move is a perfect reflect of where the Shijing stood. It was a source of knowledge about the world – be it natural, social or moral. And this is what made it a Classic. It was all the same a source of inspiration for poetry composition – and what a better clin d’œil than referring to a plant to embody an idea. This is a case where, as the subcommentary shows, the world is in the book, the book in the world, and the book in the book.