food, clothing, and other daily essentials; a metaphor for things that are indispensable though common

这些知识虽然看似平常，却如布帛菽粟，是每个人都需要的。

literal cloth, silk, beans, and grain; the fundamental materials for clothing and food

布帛菽粟是古代农耕社会维持生存的最基本物质。