Several cases: accumulation. Case: desk. Official documents, letters, books, etc. All piled up on the table. Originally refers to a large backlog of diplomas waiting to be processed. Later, it also means that there are many books or written materials.

Vastness: vastness; Sea of smoke: the vast sea. Describe the richness of classics and books.

Zuo Tu You Shi describes many indoor books.

The history of the left and right pictures is surrounded by books, which shows that they like books and are eager to learn. Same as "left picture and right history".

The history of pillows: cushions. Describe drowning in books and materials.