Page:The Harveian oration, 1875 (IA b22314611).pdf/40

 inferred, with Erasistratus, that the arteries contained only “ aerial spirits” Harvey begins his work of correction by observing that this empty state of the arterial system occurs only in that kind of death which begins in the lungs, not when the heart ceases to beat and the lungs to act at the same moment of time, as happens in more than one form of sudden death. A universal truth had therefore been assumed from a common, but still only an occasional, occurrence. And these “aerial spirits,” with which the imagination had peopled the arterial system, what were they? What their consistency? Are they separate and distinct from the blood and the solids, or mingled with them? Harvey had never been able to find any of them—neither natural spirits in the veins, nor vital spirits in the arteries, nor animal spirits in the brain or nerves. The ancients, need I say? never found an empty space in brain, heart, or arteries, but, convinced of Nature’s horror of a vacuum, they filled it with spirits. Indeed, they fancied as many spirits as there are faculties or organs. But Harvey saw in these creations of the fancy “the common subterfuge of ignorance,” alleging that “persons of limited information” used