John Sutton, December 1999
What carries messages around the body? How is information transmitted through the nervous system? What is the physical mechanism of memory? For most of this millennium, and indeed since the time of the ancient Greeks, most Westerners believed in 'animal spirits' running through their brains and bodies. We sometimes say that today we feel 'in good spirits': this is the barest metaphor, just the residue of a wonderfully rich old literal descriptive language of embodied experience.
These 'animal spirits' were, however, neither animals nor spirits. Instead, the animal spirits were fluids circulating rapidly around the nervous system between the brain and the muscles. The notion of animal spirits developed, like the Chinese qi, from ancient ideas of a psychic, animating breath: the animal spirits in our bodies were as changeable, as unpredictable as the wind. Rather like angels mediating between natural and supernatural realms, the animal spirits scoot around the body between its centre and its periphery, transmitting the commands of the will, and often distorting them too.
An 18th-century physician named Bernard Mandeville describes what happens when we try to remember something. The animal spirits, these 'volatile messengers', seek images from 'the dark caverns of oblivion' in the brain. They roam 'flying through all the mazes and meanders', they 'rummage the whole substance' of the brain, and 'ferret through its secret places with so much eagerness that it makes us uneasie'.
Belief in animal spirits, then, explained the subjective confusions of our ordinary embodied mental life. And they connected the insides to the outside world: because of their spirituous nature, these nervous fluids were vulnerable to the effects of alcoholic spirits, to music, and, dangerously, to the intrusion of evil spirits. As Philip Melanchthon warned, 'when devils occupy the heart, by their blowing they trouble the spirits in the heart and brain': and in Milton's Paradise Lost, when Satan sits 'squat like a toad, close by the ear of Eve' in the Garden, his quest to reach 'the Organs of her Fancie' works by trying to 'taint/ Th' animal spirits that from pure blood arise'.
These fleeting nervous fluids, wriggling out of the ventricles of the brain, through its neural networks, and into the body's obscure channels, thus seemed to make sense of the openness of our minds to interference and influence. Mixed up with other body fluids like blood, lymph, and semen in this oddly dynamic premodern neurophysiology, the animal spirits were a fickle medium for memory: how could we keep the past in order, or control our own histories, if memory relied on these neural fluids, so prone to spillage and confusion?
Although the animal spirits survived in mainstream scientific physiology right through the so-called Scientific Revolution of the 17th century, eventually they had to disappear. As ideals of moral self-control and mental discipline began to harden towards the end of the Enlightenment, the body’s innards had to be tamed: talk of animal spirits too easily unified emotion and intelligence, too indiscriminately linked pores and passions.
Lawrence Sterne's great novel Tristram Shandy,was written in the mid-18th century, just before the animal spirits finally retreated from medicine to metaphor. At the beginning of his tale, our hero Tristram assures us that all our successes and miscarriages in this world depend on the animal spirits' motions and activity, and the different tracks and trains you put them into. Sadly, Tristram's own sensibility is always in question, for his animal spirits have been 'ruffled beyond description' by certain unfortunate circumstances of his conception. This is not just a baroque fictional conceit, because high medical theory also linked reproduction and reasoning. Perhaps our psychology is tied to our erotic energies. As the French physician Louis de la Forge put it, 'the spirits of the brain are directly connected to the testicles. This is why men who weary their imagination in books are less suitable for procreative functions, while those who dissipate their spirits in debauching women cannot apply themselves to serious study.'
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Last updated 28 May 2000.