arterial system by the 'anastomoses'； as Galen called them； in the
lungs； that a very small portion of it entered the arteries by the
'anastomoses' in the body generally； but that the greater part of it
passed through the septum of the heart； and so entered the left side
and mingled with the pneumatised blood； which had been subjected to the
air in the lungs； and was then distributed by the arteries； and
eventually mixed with the currents of blood； coming the other way；
through the veins。
Yet one other point about the views of Galen。 He thought that both the
contractions and dilatations of the heartwhat we call the 'systole'
or contraction of the heart； and the 'diastole' or dilatationGalen
thought that these were both active movements； that the heart actively
dilated； so that it had a sort of sucking power upon the fluids which
had access to it。 And again； with respect to the movements of the
pulse； which anybody can feel at the wrist and elsewhere； Galen was of
opinion that the walls of the arteries partook of that which he
supposed to be the nature of the walls of the heart； and that they had
the power of alternately actively contracting and actively dilating； so
that he is careful to say that the nature of the pulse is comparable；
not to the movement of a bag； which we fill by blowing into it； and
which we empty by drawing the air out of it； but to the action of a
bellows； which is actively dilated and actively compressed。
Fig 3。The course of the blood from the right to the left side of the
heart （Realdus Columbus； 1559）。
After Galen's time came the collapse of the Roman Empire； the extinction
of physical knowledge； and the repression of every kind of scientific
inquiry； by its powerful and consistent enemy； the Church； and that
state of things lasted until the latter part of the Middle Ages saw the
revival of learning。 That revival of learning； so far as anatomy and
physiology are concerned； is due to the renewed influence of the
philosophers of ancient Greece； and indeed； of Galen。 Arabic
commentators had translated Galen； and portions of his works had got
into the language of the learned in the Middle Ages； in that way； but；
by the study of the classical languages； the original text became
accessible to the men who were then endeavouring to learn for
themselves something about the facts of nature。 It was a century or
more before these men； finding themselves in the presence of a
masterfinding that all their lives were occupied in attempting to
ascertain for themselves that which was familiar to himI say it took
the best part of a hundred years before they could fairly see that their
business was not to follow him； but to follow his examplenamely； to
look into the facts of nature for themselves； and to carry on； in his
spirit； the work he had begun。 That was first done by Vesalius； one of
the greatest anatomists who ever lived； but his work does not specially
bear upon the question we are now concerned with。 So far as regards
the motions of the heart and the course of the blood； the first man in
the Middle Ages； and indeed the only man who did anything which was of
real importance； was one Realdus Columbus； who was professor at Padua
in the year 1559； and published a great anatomical treatise。 What
Realdus Columbus did was this； once more resorting to the method of
Galen； turning to the living animal； experimenting； he came upon new
facts； and one of these new facts was that there was not merely a
subordinate communication between the blood of the right side of the
heart and that of the left side of the heart； through the lungs； but
that there was a constant steady current of blood； setting through the
pulmonary artery on the right side； through the lungs； and back by the
pulmonary veins to the left side of the heart （Fig。3）。 Such was the
capital discovery and demonstration of Realdus Columbus。 He is the man
who discovered what is loosely called the 'pulmonary circulation'； and
it really is quite absurd； in the face of the fact； that twenty years
afterwards we find Ambrose Pare； the great French surgeon； ascribing
this discovery to him as a matter of common notoriety； to find that
attempts are made to give the credit of it to other people。 So far as
I know； this discovery of the course of the blood through the lungs；
which is called the pulmonary circulation； is the one step in real
advance that was made between the time of Galen and the time of
Harvey。 And I would beg you to note that the word 〃circulation〃 is
improperly employed when it is applied to the course of the blood
through the lungs。 The blood from the right side of the heart； in
getting to the left side of the heart； only performs a half…circleit
does not perform a whole circleit does not return to the place from
whence it started； and hence the discovery of the so…called 〃pulmonary
circulation〃 has nothing whatever to do with that greater discovery
which I shall point out to you by…and…by was made by Harvey； and which
is alone really entitled to the name of the circulation of the blood。
If anybody wants to understand what Harvey's great desert really was； I
would suggest to him that he devote himself to a course of reading；
which I cannot promise shall be very entertaining； but which； in this
respect at any rate； will be highly instructivenamely； the works of
the anatomists of the latter part of the 16th century and the beginning
of the 17th century。 If anybody will take the trouble to do that which
I have thought it my business to do； he will find that the doctrines
respecting the action of the heart and the motion of the blood which
were taught in every university in Europe； whether in Padua or in Paris；
were essentially those put forward by Galen； 'plus' the discovery of
the pulmonary course of the blood which had been made by Realdus
Columbus。 In every chair of anatomy and physiology （which studies were
not then separated） in Europe； it was taught that the blood brought to
the liver by the portal vein； and carried out of the liver to the 'vena
cava' by the hepatic vein； is distributed from the right side of the
heart； through the other veins； to all parts of the body； that the
blood of the arteries takes a like course from the heart towards the
periphery； and that it is there； by means of the 'anastomoses'； more or
less mixed up with the venous blood。 It so happens； by a curious
chance； that up to the year 1625 there was at Padua； which was Harvey's
own university； a very distinguished professor； Spigelius； whose work
is extant； and who teaches exactly what I am now telling you。 It is
perfectly true that； some time before； Harvey's master； Fabricius； had
not only re…discovered； but had drawn much attention to certain
pouch…like structures； which are called the valves of the veins； found
in the muscular parts of the body； all of which are directed towards
the heart； and consequently impede the flow of the blood in the
opposite direction。 And you will find it stated by people who have not
thought much about the matter； that it was this discovery of the valves
of the veins which led Harvey to imagine the course of the circulation
of the blood。 Now it did not lead Harvey to imagine anything of the
kind。 He had heard all about it from his master； Fabricius； who made a
great point of these valves in the veins； and he had heard the theories
which Fabricius entertained upon the subject； whose impression as to
the use of the valves was simply thisthat they tended to take off any
excess of pressure of the blood in passing from the heart to the
extremities； for Fabricius believed； with the rest of the world； that
the blood in the veins flowed from the heart towards the extremities。
This； under the circumstances； was as good a theory as any other；
because the action of the valves depends altogether upon the form and
nature of the walls of the structures in which they are attached； and
without accurate experiment； it was impossible to say whether the
theory of Fabricius was right or wrong。 But we not only have the
evidence of the facts themselves that these could tell Harvey nothing
about the circulation； but we have his own distinct declaration as to
the considerations which led him to the true theory of the circulation
of the blood； and amongst these the valves of the veins are not
mentioned。
Fig。 4。The circulation of the blood as demonstrated by Harvey （A。D。
1628）。
Now then we may come to Harvey himself。 When you read Harvey's
treatise； which is one of the most remarkable scientific monographs
with which I am acquaintedit occupies between 50 and 60 pages of a
small quarto in Latin； and is as terse and concise as it possibly can
bewhen you come to look at Harvey's work； you will find that he had
long struggled with the difficulties of the accepted doctrine of the
circulation。 He had received from Fabricius； and from all the great
authorities of the day； the current view of the circulation of the
blood。 But he was a man with that rarest of all
qualitiesintellectual honesty； and by dint of cultivating that great
faculty； which is more moral than intellectual； it had become impossible
for him to say he believed anything which he did not clearly believe。
This is a most uncomfortable peculiarityfor it gets you into all
sorts of difficulties with all sorts of peoplebut； for scientific
purposes； it is absolutely invaluable。 Harvey possessed this
peculiarity in the highest degree； and so it was impossible for him to
accept what all the authorities told him； and he looked into the matter
for himself。 But he was not hasty。 He worked at his new views； and he
lectured about them at the College of Physicians for nine years； he did
not print them until he was a man of fifty years of age； and when he
did print them he accompanied them with a demonstration which has never
been shaken； and which will stand till the end of time。 What Harvey
proved； in short； was this （see Fig。 4）that everybody had made a
mistake； for want of sufficiently accurate experimentation as to the
actual existence of the fact which everybody assumed。 To anybody who
looks at the blood…vessels with an unprejudiced eye it seems so natural