Again, in the work _On the Art_ [_of Medicine_] we read: 'I hold it to be physicianly to abstain from treating those who are overwhelmed by disease',[74] a prudent if inhumane procedure among a people who might regard the doctor's powers as partaking of the nature of magic, and perhaps a wise course to follow at this day in some places not very far from Cos. Yet in the book _On Diseases_ we are advised even in the presence of an incurable disease 'to give relief with such treatment as is possible'.[75] [74] Περι τεχνης {Peri technês}, § 3. [75] Περι νουσων α' {Peri nousôn a'}, § 6. Furthermore, works by authors of the Hippocratic school stand sometimes in a position of direct controversy with each other. Thus in the treatise _On the Heart_ an experiment is set forth which is held to prove that a part at least of imbibed fluid passes into the cavity of the lung and thence to the parts of the body, a popular error in antiquity which recurs in Plato's _Timaeus_. This view, however, is specifically held to be fallacious by the author of the work _On Diseases_, who is supported by a polemical section in the surviving Menon fragment. Passages like these have convinced all students that we have to deal in this collection with a variety of works written at different dates by different authors and under different conditions, a state that may be well understood when we reflect that among the Greeks medicine was a progressive study for a far longer period of time than has yet been the case in the Western world. An account of such a collection can therefore only be given in the most general fashion. The system or systems of medicine that we shall thus attempt to describe was in vogue up to the Alexandrian period, that is, to the beginning of the third century B. C.