Reading and writing fill in the blanks
Modern technology has enhanced the study of language by making its sounds observable in greater detail and with greater accuracy than ever before, but the thoughts associated with those sounds remain problematic. Currently developing of brain imaging are allowing us to observe for the first-time which parts of the brain are active in different circumstances. They do not, however, show experiences themselves, which may always remain from public observation. There is a sense in which each of us knows what we are thinking, we may not always have a good way of verbalizing it. But the only way we can know what someone else is thinking is through what that person says, or through some other overt action, a facial expression or gesture, perhaps from which that person's thoughts may be inferred, or from imagining what we ourselves would be thinking similar circumstances.