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The Birth of a Problem

1. The Eighteenth-century Background: Sensibility, Sympathy & Nervous Diseases 1750–1800 Bynum1 has characterized the second half of the eighteenth century as a period in which the hold of Hippocratic humoralism was being eroded and the importance of the nervous system in health and disease increasingly emphasized. This shift was played out in writings on sensibility and sympathy, some of the most famous of which will be briefly summarized as background to our period of interest.

Sensibility Rey is quite clear that ‘sensibility was a physiological concept before it was a psychological or aesthetic one’2 while Mullan 3 highlights the shared vocabulary and, by implication, the interdependence of the literary and medical fields at mid-century. Much can be made of the fact that the author of The English Malady of 1733,4 George Cheyne, was the physician and friend of Samuel Richardson, the novelist of sentiment. Both wrote of sensibility as a blessing and a curse, a result of progress, a sign of intellect and refinement, yet a feature that could take a person close to insanity. Sensibility was also of new importance as the starting point for epistemology in Locke’s empiricism and Condillac’s sensualism. But, according to Rey, it was the precise definition and the beginnings of measurement of it that were to prove of greatest heuristic value. The starting point of this endeavour is generally taken to be Albrecht von Haller’s 1752 lectures to George II’s ‘Royal Society’ in Göttingen. 5 Haller defined sensibility as follows: I call that a sensible part of the human body , which on being touched transmits the impression of it to the soul; and in brutes, in which 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. 6 Thus sensibility was a property of a body part. Some parts, such as

25 The Birth of a Problem bone marrow and tendons, did not possess it. Note that from this famous beginning, pain was taken to be the exemplar of sensibility. Both Robert Whytt in Edinburgh and the Montpellier Vitalists objected to Haller’s definition. Whytt regarded sensibility as a property of the brain and spinal cord rather than peripheral nerves. This was for metaphysical, if not theological, reasons according to French7 and Brazier. 8 Whytt has been depicted as an Animist, arguing for the intervention of an immaterial soul in physiological processes. He was most reluctant to endow mere peripheral nerves with the ‘sentient principle’, though he did concede that the spinal cord had it. The latter was a conclusion based on observation of decapitated animals and pithed frogs. The Montpellier Vitalists insisted that the whole body has sensibility by virtue of being alive. They could not accept Haller’s view that certain parts lacked it. They were also very aware that the conditions of Haller’s vivisections might have affected his findings. For example, the pain of a skin incision might obscure the sensibility of the exposed part. 9 Cullen’s concept of sensibility was similar to that of his Edinburgh forbear, Whytt. He too ‘placed’ sensibility in the brain and spinal cord rather than peripheral body parts. However, Lawrence 10 has convincingly pointed out an additional crucial influence on Cullen’s account of sensation from the Scottish philosopher David Hume. Cullen divided mental events into sensations and ideas. Sensations, like Humean ‘Impressions’, were states of feeling as opposed to Ideas, which were the faint images of these in thought. Sensations were fully determined states of feeling which presented irresistibly to the subject’s consciousness. However, ideas came and went from attention, with or without the subject’ s volition, as imaginings and memories. Cullen split sensations further according to their origin. They might arise from external events (e.g. the cut of a knife) or by internal events (e.g. the passions or emotions) coming to attention. He mentioned a number of factors involved in determining sensations, freely mixing variables as diverse as the physical condition of the nerves and the subject’s level of attentiveness. Painful experience generated fear and aversion and influenced mood. ‘ Sensation then...was the basis of the whole of Cullen’s physiology and epistemology’. 11 That Cullen derived such a complex theory of perception from Hume may surprise those familiar with empiricist readings of the latter’s philosophy. However, the proximity of Humean ‘Impressions’ to the ‘ sense data ’ of logical positivism was probably overstated in early twentieth-century histories of philosophy for polemical reasons. Across the Channel, Condillac’s Traité des Sensations of 175412 26