thought was not different from the heat in hay that has been heaped
together before it is dry, or that which causes fermentation in new wines
before they are run clear of the fruit. For, when I examined the kind of
functions which might, as consequences of this supposition, exist in this
body, I found precisely all those which may exist in us independently of
all power of thinking, and consequently without being in any measure owing
to the soul; in other words, to that part of us which is distinct from the
body, and of which it has been said above that the nature distinctively
consists in thinking, functions in which the animals void of reason may be
said wholly to resemble us; but among which I could not discover any of
those that, as dependent on thought alone, belong to us as men, while, on
the other hand, I did afterwards discover these as soon as I supposed God
to have created a rational soul, and to have annexed it to this body in a
particular manner which I described.

But, in order to show how I there handled this matter, I mean here to give
the explication of the motion of the heart and arteries, which, as the
first and most general motion observed in animals, will afford the means
of readily determining what should be thought of all the rest. And that
there may be less difficulty in understanding what I am about to say on
this subject, I advise those who are not versed in anatomy, before they
commence the perusal of these observations, to take the trouble of getting
dissected in their presence the heart of some large animal possessed of
lungs (for this is throughout sufficiently like the human), and to have
shown to them its two ventricles or cavities: in the first place, that in
the right side, with which correspond two very ample tubes, viz., the
hollow vein (vena cava), which is the principal receptacle of the blood,
and the trunk of the tree, as it were, of which all the other veins in the
body are branches; and the arterial vein (vena arteriosa), inappropriately
so denominated, since it is in truth only an artery, which, taking its