Sir

I was intrigued by recent letters about the Chinese medical treatise Su Wên and its apparent account of blood circulation. Prioreschi's argument (Nature 405, 993; 2000), based on uncertainty about the exact meaning of certain words, is insufficient to disqualify the ancient Chinese as the discoverers of blood circulation. One's conclusion can be biased by the choice of translator as well as the translator's choice of words: an inevitable problem since this argument relies on excerpts of translated materials.

In order to make a fair judgement, one would have to consult the ancient Chinese text directly and treat the technical terms in accordance with standard definitions, as one would do with any other technical literature.

Until ancient Chinese knowledge of blood circulation is proved or disproved in an appropriate manner, it is safe just to say that Harvey made the suggestion that elicited the documented scientific experiments proving how the blood circulates.