But Needham also pointed out that the ancient Chinese conception of physiology differs from the modern one in that it envisages two parallel systems, the existence of one of which (for the blood) can be demonstrated by anatomists, while the second (for chi) cannot.
但他也同時指出，這個古代的生理學系統與現代觀念偏離的地方在於它有兩個平行的循環系統（血和氣），一個可由解剖學證實（血），一個則無法證實（氣）。