Chapter 5 dealt with Lewis's theory of what the mind is, and how to identify mental states with physical states. This chapter also deals with part of the theory of mind: what is it for a mental state to mean something, to be about an aspect of the world? What makes my belief that dolphins live in the ocean that sort of belief, rather than a belief that dolphins live in mountains (or, for that matter, rather than the belief that there are eggs in my fridge)? In turn, armed with an account of what it is for a mental state to have a “content” (that is, a meaning, or a specification of what it is about), we shall be in a position to tackle the question in Chapter 7: what is it for a piece of language, or some communicative act, to have a meaning or be about something? What makes the pattern of ink marks “wombat” be about a certain kind of small mammal rather than about the ocean or cosmic radiation? Some people try to tackle the question about language and public meaning first, and only then turn to the question of mental content. Lewis's account of language use, on the other hand, relies on being able to make antecedent sense of the beliefs, desires and intentions of speakers; so it relies on there being an adequate answer to questions about what gives these beliefs, desires and intentions their content.