This means one should acquire as much knowledge as possible from books to gain the experience of others. At the same time, one should also have as much direct contact with the world as possible to enrich one's personal experience and broaden one's horizon. When one applies theory in practice and draws on both direct and indirect experience, he will gain true knowledge.

What aspiration should one have? Travel ten thousand li to see the world, and read ten thousand books. (Gao Shiqi: Miscellaneous Notes on Escorting Journeys)