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 Figure
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 that the blood should all come out of the liver,
and be distributed by the veins to the different parts of the body, that
nothing can seem simpler or more plain; and consequently no one could
make up his mind to dispute this apparently obvious assumption. But
Harvey did dispute it; and when he came to investigate the matter he
discovered that it was a profound mistake, and that, all this time, the
blood had been moving in just the opposite direction, namely, from the
small ramifications of the veins towards the right side of the heart.
Harvey further found that, in the arteries, the blood, as had previously
been known, was travelling from the greater trunks towards the
ramifications. Moreover, referring to the ideas of Columbus and of Galen
(for he was a great student of literature, and did justice to all his
predecessors), Harvey accepts and strengthens their view of the course
of the blood through the lungs, and he shows how it fitted into his
general scheme. If you will follow the course of the arrows in Figure 4
you will see at once that--in accordance with the views of Columbus--the
blood passes from the right side of the heart, through the lungs, to the
left side. Then, adds Harvey, with abundant proof, it passes through the
arteries to all parts of the body; and then, at the extremities of their
branches in the different parts of the body, it passes (in what way he
could not tell, for his means of investigation did not allow him to say)
into the roots of the vents--then from the roots of the veins it goes
into the trunk and veins--then to the right side of the heart--and
then to the lungs, and so on. That, you will observe, makes a complete
circuit; and it was precisely here that the originality of Harvey lay.
There never yet has been pro