36
HARVEY AND GALEN
came the master mind of Harvey, which arranged the letters in the right order, and so the word was spelt for all the world to read. To do this required that peculiar high faculty of synthesis which is rightly regarded as an attribute of genius, and is closely allied to the poetical imagination. This faculty seems not always to follow the strict chain of reasoning, link after link, or to result from a mere collect- ing and marshalling of the data, however skilful, as Bacon supposed. The creation of the poet is generated in his mind from pre-existing sensations and ideas by a process which he cannot understand himself, and which the great poets have spoken of reverently as a kind of inspiration. So the idea of a great discoverer or inventor is generated by some process of which he himself may be only partly conscious ; and a new form, like that idea of Harvey’s of a circular motion , results. The difference is that the scientific idea, unlike the poetical, requires to be carefully verified and proved — a process which Harvey himself was the last to neglect.
Further to illustrate Galen’s scientific method, I should like to say something about his physiology of the nervous system, to which justice has hardly been done, but which was certainly his greatest achievement. My object now is merely to show that Galen’s method in investigating this subject was the only true one of observation and experi- ment, not to dwell upon his results, though they were very considerable. Before entering on this subject I should like to say a word on one point in which a difference of language makes Galen’s views seem much more different from modern physiology than they really were — the old and famous doctrine of the animal spirits. He explained nervous action, both motion and sensation, by something
of the veins, and having had this figure executed to show the effect on the valves of ligaturing the veins on the cardiac side, should not have the slightest inkling of their real use. He thought them designed to prevent excessive dilatation or too
rapid a current in the veins, espe- cially in the direction of gravitation. The valves at the commencement of the jugular veins, he thought, would only come into operation when the animal or man bent the head down- wards.
