Extract from "Letters upon Italy, chiefly concerning the present state of medicine and natural history [...]", by W Jansen, physician of Düsseldorf, [Germany], sent by Aufrere following a comment in Smith's "Tour upon the Continent" that he had not seen the book written by Prof Michael Rosa to invalidate the Harverian system. The extract relates Rosa's theory of the circulatory system, in which the arteries of men and large beasts "contain only a small quantity of blood but are filled with a spirit or spiritous essence".