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I was not； however； disposed； from these circumstances； to conclude that
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this world had been created in the manner I described； for it is much more
likely that God made it at the first such as it was to be。 But this is certain；
and an opinion monly received among theologians； that the action by
which he now sustains it is the same with that by which he originally
created it； so that even although he had from the beginning given it no
other form than that of chaos； provided only he had established certain
laws of nature； and had lent it his concurrence to enable it to act as it is
wont to do； it may be believed； without discredit to the miracle of creation；
that； in this way alone； things purely material might； in course of time；
have bee such as we observe them at present； and their nature is much
more easily conceived when they are beheld ing in this manner
gradually into existence； than when they are only considered as produced
at once in a finished and perfect state。
From the description of inanimate bodies and plants； I passed to
animals； and particularly to man。 But since I had not as yet sufficient
knowledge to enable me to treat of these in the same manner as of the rest；
that is to say； by deducing effects from their causes； and by showing from
what elements and in what manner nature must produce them； I remained
satisfied with the supposition that God formed the body of man wholly
like to one of ours； as well in the external shape of the members as in the
internal conformation of the organs； of the same matter with that I had
described； and at first placed in it no rational soul； nor any other principle；
in room of the vegetative or sensitive soul； beyond kindling in the heart
one of those fires without light； such as I had already described； and which
I 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
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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
mence 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 rise in the
heart； is divided； after passing out from it； into many branches which
presently disperse themselves all over the lungs； in the second place； the
cavity in the left side； with which correspond in the same manner two
canals in size equal to or larger than the preceding； viz。； the venous artery
（arteria venosa）； likewise inappropriately thus designated； because it is
simply a vein which es from the lungs； where it is divided into many
branches； interlaced with those of the arterial vein； and those of the tube
called the windpipe； through which the air we breathe enters； and the great
artery which； issuing from the heart； sends its branches all over the body。
I should wish also that such persons were carefully shown the eleven
pellicles which； like so many small valves； open and shut the four orifices
that are in these two cavities； viz。； three at the entrance of the hollow veins
where they are disposed in such a manner as by no means to prevent the
blood which it contains from flowing into the right ventricle of the heart；
and yet exactly to prevent its flowing out； three at the entrance to the
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arterial vein； which； arranged in a manner exactly the opposite of the
former； readily permit the blood contained in this cavity to pass into the
lungs； but hinder that contained in the lungs from returning to this cavity；
and； in like manner； two others at the mouth of the venous artery； which
allow the blood from the lungs to flow into the left cavity of the heart； but
preclude its return； and three at the mouth of the great artery； which suffer
the blood to flow from the heart； but prevent its reflux。 Nor do we need
to seek any other reason for the number of these pellicles beyond this that
the orifice of the venous artery being of an oval shape from the nature of
its situation； can be adequately closed with two； w