One individual helps another to keep track of a changing world by drawing its attention to properties. The second individual has access to the changed world. Input is from the informant and the world. One individual helps another to keep track of a changing world by drawing its attention to properties. The second individual has no access to the changed world.
Input is from the informant only.
This vocabulary may be either innate or learned. Such utterances can be more or less under volitional control. To achieve a unified theory of language, specifying the relationships between structure and use, diachrony and synchrony, ontogeny and phylogeny.