Page:The Harveian oration 1896.djvu/41

GALEN ON THE NERVOUS SYSTEM

37 descending from the brain through the nerves to the muscles and other parts. This something he called ^/vlkov 7rve0jLca, a phrase of which the modern translation through two languages into ‘animal spirits’ is somewhat misleading, being the origin of all our colloquial phrases about high and low spirits, and so on. The original meaning is rather ‘ breath of the soul,’ or breath belonging to the c psyche.’ The word ‘ psyche ’ itself is difficult to render ; soul, mind, consciousness, the sensorium, &c., all have other connota- tions, and so I find that some modern psychologists prefer to use the old term ‘ psyche ’ for that which we suppose to be manifested through the brain. I cannot suggest any better definition of the ‘psyche’ than the tautological one that it is the subject of the science of psychology. The ‘pneuma’ was supposed to be some kind of air or very subtle fluid capable of traversing the solid nerves. Our modern expression for what traverses the nerves is ‘nerve force.’ But I am not sure that ‘nerve force’ is a much more scientific expression, since the correlation of this force with physical forces is by no means rigidly established. It seems to be a convenient expression for something the nature of which we do not know ; though in this I may be perhaps a little heretical.

However, in justice to Galen’s ignorance we should remember that it was only the other day we were taught in every text-book of physics that electricity and magnetism were subtle fluids, and we were. sometimes given the choice between the single fluid and the double fluid hypothesis. ‘ Electric fluid ’ is a vernacular phrase. The term ‘nervous fluid’ was retained in text-books of physiology which some of us learned from, and between nervous fluid and nervous pneuma there seems little to choose. The hypotheses of electric, magnetic, and nervous fluids no doubt explained many phenomena fairly well, till it was found there were other phenomena which they did not explain, and so they were given up. Galen un- fortunately materialized his pneuma too much, supposing it to be included, like air, in the ventricles of the brain.