Literature (poetry), aesthetics (color matching, clothing and jewelry matching mentioned by Baochai when Baoyu wants to tie the network), economics (changing money for financial management), architecture (Grand View Garden), folk customs (various birthday and holiday games, etc.). ), teaching theory (said by Daiyu when she taught Xiangling to write poems), nutrition (seen by Jia Mu) and management (said by Xifeng of Ningguo) are all big categories, and there are many occupations or names unique to that era revealed between the lines. For example, the way mules walk reminds people of the caravan that doesn't exist now, and reminds people of pawn shops. Nowadays, pawn shops in ancient times are rare. The new pawnshops have lost that smell. They are almost like shops. Others have declined or disappeared now, or even more. Not to mention the details, each category can be divided into many specific subcategories.