Some of the earliest works of the corpus (mid-fifth century) are connected to the Cnidian school: "On Diseases" II–III and the early layer within "On the Diseases of Women" I–II and "On Sterile Women". "Prorrhetics" I is also mid-fifth century. In the second half of the fifth century, a single author likely produced the treatises "On Airs, Waters, Places"; "Prognostics"; "Prorrhetics" II; and "On the Sacred Disease". Other fifth-century works include "On Fleshes", "Epidemics" I and III (c. 410 BC), "On Ancient Medicine", "On Regimen in Acute Diseases", and Polybus' "On the Nature of Man"/"Regimen in Health" (410–400 BC).