On the Different Forms of Insanity


James Prichard was an early-nineteenth century physician who developed the idea of ‘moral insanity’. He initially proposed this as a state in which ‘the active powers are primarily disordered, without any affection of the intellectual faculties’ (A Treatise on Diseases of the Nervous System, 1822). ‘Moral insanity’ came to be seen as a distortion of the emotions and a sign of moral perversion, which did not have any noticeable effect on the intellect. 

Where do these ideas appear in Robert Louis Stevenson's Strange Case of Dr Jekyll and Mr Hyde

In Robert Louis Stevenson's Strange Case of Dr Jekyll and Mr Hyde Dr Jekyll’s ‘creation’ of Hyde, and the way that being Hyde allows him to explore amorality, gives Jekyll the opportunity to avoid the classification of ‘moral insanity’ himself. By the end of the 19th century, this had come to be seen as a psychiatric condition in which wealthy and responsible adult males were seen as abandoning behaviour appropriate to their class and status. 

Jekyll’s companions view with alarm his behaviour – shutting himself away, refusing to trust Lanyon with his secret, appearing to be suspicious of his friends; by not behaving by the rules of his class, he is threatening them. His actions are seen as a ‘case’ by his peers, who are doctors and lawyers. 

Robert Mighall points out[1] that Jekyll/Hyde’s pattern of behaviour, swinging between embracing the amoral actions of Hyde and the remorse of Jekyll, is typical of the pathology of the morally insane, as seen in this case described by James Prichard. 

[1] Robert Louis Stevenson, Strange Case of Dr Jekyll and Mr Hyde (Penguin Classics, 2003), pp. 146-47

Full title:
On the Different Forms of Insanity in Relation to Jurisprudence, designed for the use of persons concerned in legal questions regarding unsoundness of mind.
1842, London
Prichard James Cowles
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Public Domain
Held by
British Library

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