were, two pouches denominated the auricles of the heart, which are
composed of a substance similar to that of the heart itself; and that
there is always more warmth in the heart than in any other part of the
body- and finally, that this heat is capable of causing any drop of blood
that passes into the cavities rapidly to expand and dilate, just as all
liquors do when allowed to fall drop by drop into a highly heated vessel.

For, after these things, it is not necessary for me to say anything more
with a view to explain the motion of the heart, except that when its
cavities are not full of blood, into these the blood of necessity flows, -
- from the hollow vein into the right, and from the venous artery into the
left; because these two vessels are always full of blood, and their
orifices, which are turned towards the heart, cannot then be closed. But
as soon as two drops of blood have thus passed, one into each of the
cavities, these drops which cannot but be very large, because the orifices
through which they pass are wide, and the vessels from which they come
full of blood, are immediately rarefied, and dilated by the heat they meet
with. In this way they cause the whole heart to expand, and at the same
time press home and shut the five small valves that are at the entrances
of the two vessels from which they flow, and thus prevent any more blood
from coming down into the heart, and becoming more and more rarefied, they
push open the six small valves that are in the orifices of the other two
vessels, through which they pass out, causing in this way all the branches
of the arterial vein and of the grand artery to expand almost
simultaneously with the heart which immediately thereafter begins to
contract, as do also the arteries, because the blood that has entered them
has cooled, and the six small valves close, and the five of the hollow
vein and of the venous artery open anew and allow a passage to other two
drops of blood, which cause the heart and the arteries again to expand as
before. And, because the blood which thus enters into the heart passes