Pots" and other large vessels in the Bible represent facts and factual ideas, which serve as containers for truth the same way pots serve as containers for water or wine. Pots fill their function because they are hard, strong and impervious; facts are also absolute and unchanging, filling their function the same way. And pots must be filled to serve any use, just as facts must be filled with truth to serve any purpose. To some extent this meaning also applies to cups, bowls and other smaller vessels, though it is a little more immediate. Generally you don't fill a cup so you can store a liquid; you fill it to drink it. Smaller vessels then often take more of their meaning from the substance they contain, and in many cases ("cup" and "wine" especially) actually mean the same thing.