e in the manner
already indicated; which motion we may be allowed to call circular, in
the same way as Aristotle says that the air and the rain emulate the
circular motion of the superior bodies. For the moist earth, warmed by
the sun, evaporates; the vapours drawn upwards are condensed, and
descending in the form of rain moisten the earth again. And by this
arrangement are generations of living things produced; and in like
manner, too, are tempests and meteors engendered by the circular motion
of the sun.

And so in all likelihood does it come to pass in the body through the
motion of the blood. The various parts are nourished, cherished,
quickened by the warmer, more perfect, vaporous, spirituous, and, as I
may say, alimentive blood; which, on the contrary, in contact with these
parts becomes cooled, coagulated, and, so to speak, effete; whence it
returns to its sovereign, the heart, as if to its source, or to the
inmost home of the body, there to recover its state of excellence or
perfection. Here it resumes its due fluidity, and receives an infusion
of natural heat--powerful, fervid, a kind of treasury of life--and is
impregnated with spirits and, it might be said, with balsam; and thence
it is again dispersed. And all this depends upon the motion and action
of the heart.

_Confirmations of the Theory_

Three points present themselves for confirmation, which, being
established, I conceive that the truth I contend for will follow
necessarily and appear as a thing obvious to all.

The first point is this. The blood is incessantly transmitted by the
action of the heart from the _vena cava_ to the arteries in such
quantity that it cannot be supplied from the ingesta, and in such wise
that the whole mass must very quickly pass through the organ.

Let us assume the quantity of blood which the left ventricle of the
heart will contain when distended to be, say, two ounces (in the dead
body I have found it to contain upwards of two ounces); and let us
suppose, as approaching the truth, that the fourth part of its charge
is thrown into the artery at each contraction. Now, in the course of
half an hour the heart will have made more than one thousand beats.
Multiplying the number of drachms propelled by the number of pulses, we
shall have one thousand half-ounces sent from this organ into the
artery; a larger quantity than is contained in the whole body. This
truth, indeed, presents itself obviously before us when we co