The next stage is represented by anatomy, which is in turn followed by the study of the function (chreia), capacities (dunameis) and activities of the parts which anatomy reveals. Capacities both “of nature” (phusikai) and “of the soul” (psuchikai) are considered here: the important work Natural Capacities (Nat. Fac.) is especially relevant to the former, PHP and The Motion of Muscles (Mot. Musc.) to the latter; study of UP should follow here too.