Part One is an account of the range of contents which human thoughts can have. This is not the only way to focus a theory of content, and it is not unproblematic. It is not unproblematic even if our human form is relevant to what we can think. Even if there is some single paradigm of normal adult human neurophysiology, still other humans differ from that paradigm in relevant ways. At best, we can hope only to provide an account of content for "normal" adult humans. And even "normal" adult humans may relevantly differ, so that some idealization unavoidably infects our account. Also, any biological constraints we humans now suffer may one day be broken by technological advance, which will allow us to alter our form. Despite the legitimacy of these worries, the account which follows will show that normal adult human capacities are, at least for now, at least enough alike to make a focus on "human" content reasonable.