Several other contemporary investigators might have strongly influenced her development of the moral/spiritual issues and scientific basis for the book, and acted as a source for Frankenstein. For some three or four decades before the novel, study of ‘vital animation’ had been ongoing in nearby Germany, Italy and Switzerland, and these new concepts on the nature of neuromuscular function began permeating the teaching curricula of medical schools². In 1752, Albrecht Haller of Switzerland, in particular, propagated his theory of muscle ‘irritability’ and nerve ‘sensibility’, at odds with Glisson's idea that the soul was the generator of voluntary movements. Haller's ‘irritability’ was the property by which a part of the human body³ ‘... becomes shorter on being touched... [while] that sensible part of the human body, which on being touched transmits the impression of it to the soul; and in brutes, the existence of a soul is not so clear, I call those parts sensible, the irritation of which occasions evident signs of pain and disquiet in the animal’. (Are there not echoes here of the animation of Frankenstein's inanimate brute evoking the concept of the reconstituted human without a soul?) In 1762, Haller's magnum opus⁴ was published in Lausanne, across the lake from the Villa Diodati and ‘the house of Frankenstein’ at Belrive.

In contrast, Georg Stahl, a ‘vitalist’, claimed that only the ‘anima’ could regulate bodily activity² at death. Curiously enough, this vitalistic approach was linked neither to God nor to any religious doctrine. As Brazier notes, ‘hovering between mind and brain is the ghost of the soul... less confusing for English speakers for they have a noun for “mind”, as distinct from “soul” or “spirit”. The French do not (which raises problems concerning Descartes' intended meanings)²’. Here again are the echoes of Mary Shelley's moral dilemma: was there a soul or a spirit in the monster? There clearly was a mind.

Johann Unzer, in Hamburg, divided neuromuscular activity into voluntary, involuntary and unconscious types. Unzer believed that even headless animals remained alive in that they continued to have ‘animal spirits’ within their nerves. To illustrate the ‘unconscious’ as occurring in animals without a brain or soul, he used decapitated frogs to show that nerve stimulation alone could induce movement.

All these investigators, however, failed to conceive of the possibility of electricity being the inciting element in tissue irritability, until Caldani, the anatomist, provided electricity from a frictional electrostatic machine to stimulate muscles in sheep and frogs: ‘An electrified rod was brought within one, two or three inches... and we always saw the muscles of the lower extremity make a movement... without a spark being evoked⁵’.

Early in the 18th century, frictional machines were used to produce sparks and static electricity, much to the entertainment of the leisured classes. The recently invented Leyden jar enabled a sudden electrical discharge to pass to tissues under experiment which then led to the use of this tool in electrophysiological experiments. As Musschenbroek relates: ‘I want to tell you of a new but terrible experiment which I advise you never to attempt yourself... the arm and the whole body was affected in so terrible a manner that I cannot express: in a word I thought it was the end of me’⁶.

The power of this new electricity used alone was soon amply illustrated by Nollet who lined up a chain of men two miles long, causing them to jump when touching the poles of a Leyden jar². At age 34, Nollet travelled to England and was elected to the Royal Society. His lectures on electricité foudroyante led to speculation that electricity could vitalize a paralysed human⁷. One such patient reported a ‘tingling in his arms that he had not felt for many years’. Nollet subsequently suspended a naked and partly paralysed patient in a swing, insulated by silk ropes suspended from the ceiling. Iron wire wrapped around the body was connected to a frictional machine, producing sparks to an iron bar near the paralysed limb².

Foreshadowing the reanimation evoked in ‘Frankenstein’, Galvani in Italy progressed from working with ‘artifical electricity’ to using ‘atmospheric electricity’—lightning during a thunderstorm⁸—to stimulate contraction in the legs of a living frog. Galvani's nephew Aldani would stand by the guillotine, and take freshly decapitated heads of criminals, pass a current through the mouth and ear or exposed brain and mouth, evoking facial grimaces, thus simulating a return to life².

We can now more clearly see the similarity to Mary Shelley's Frankenstein in these attempts to animate paralysed limbs by means of static electricity in a patient suspended from the ceiling, and in Galvani's harnessing of electricity from the heavens during a lightning storm to reanimate dead muscles. As recalled by Mary in the 1831 edition of Frankenstein, ‘perhaps a corpse could be reanimated, galvanism had given token of such things. Perhaps the component parts of a creature could be manufactured... and endued with vital warmth’.

But out of the shadows of Krüger, an investigator of the late 18th century, stepped his pupil, a highly vocal prosyletizer of electrotherapy. Using frictional electricity, he induced movement in paralysed fingers, and even induced ‘electro-sleep’ in humans. The name of this disciple of electrical reanimation was... Kratzenstein⁹.