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 acquainted—it occupies between 50 and 60 pages of a small quarto in Latin, and is as terse and concise as it possibly can be—when 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 qualities—intellectual 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 peculiarity—for it gets you into all sorts of difficulties with all sorts of people—but, 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 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.