On the Heart, or De
Corde trans. by I.M. Lonie in Lloyd, G.E.R., Hippocratic Writings.
London: Penguin Books, 1978, pp. 347-351, ch. 12.
12. As for the vessel which comes from the right chamber, this too is closed
off by the membranes meeting together. But they are too weak to close it
completely. It opens toward the lung to provide blood for the lung's
nutriment, while towards the heart it is closed. but not hermetically, so that
air can enter it, though only in a very small quantity. For in this part the
heat is weak, being dominated by a mixture of cold. Contrary to the general
opinion, blood is in fact not a hot thing by nature, any more than any other
fluid; though it may be made hot.
Such, then, is my description of the heart.