After raising difficulties regarding not-being, the Visitor and Theaetetus become involved with puzzles about being. This is rather surprising because one might have expected the obscurity to be confined to the obviously problematic area of not-being. The puzzles about being come in two families.

The present chapter’s first section addresses the first family of puzzles (243d6–245e5), which concern the number of beings. Both pluralists, who believe there to be two or more entities, and monists, who maintain that only one thing is, are criticized. The second family of puzzles about being (245e6–249d8), tackled in this chapter’s second section, concerns the characteristics shared by all and only beings. A debate is set up between two factions. One party includes thinkers who claim that only bodies are, members of the other hold instead that only changeless forms are. An attempt to reach a compromise acceptable to both parties leads to the result that both change and stability are beings. But then (249d9–250d4) a further difficulty arises which seems to depend on a confusion between sentences used to speak about the kind being itself. This last difficulty is dealt with in the chapter’s third section.