Charles Mercier (1851-1919) wrote his Text-Book on Insanity in 1902; it’s more straight-laced than most, and the following section should be read in your best Mr Cholmondley-Warner voice. (In the final paragraph, Mercier is unable to deal with the love that dared not speak its name – just cannot even countenance its existence.)

“MORAL PERVERSION”
“The fabric of morality rests upon a single foundation, viz., the ability to forgo a pleasure or incur a pain, now, upon the instant, in order that by our present self-denial we may secure benefit hereafter. Lack of this ability is evinced in vice, by which is meant immediate indulgence at the cost of disproportionate detriment hereafter. When vice is pushed to excess, it becomes insanity; and there are certain forms of insanity that are characterised, if not entirely, yet mainly and most conspicuously, by the excess of vice as here defined…

“There are persons who indulge in vices with such persistence, at the cost of punishment so heavy, so certain, and so prompt, who incur this punishment for the sake of pleasure so trifling and so transient, that they are by common consent considered insane, although they exhibit no other indication of insanity.

“The following cases are illustrative of moral insanity: an Afghan who had been deprived first of his right hand and then of his left, struck off in punishment for theft, seized with his stumps, and made off with, an earthenware pot of very trifling value, and did this under the very eyes of the police, well knowing that he would probably be hanged next morning, as in fact he was. A lad at college, the son of well-to-do parents, who kept him well supplied with clothes and made him an ample allowance, stole a suit of clothes and a pair of boots from a fellow student. He was seen to come away from his fellow student’s room with the clothes under his arm, but though he lied elaborately when taxed with the theft, he made no effort to conceal the stolen things, but left them lying about his room. He was expelled and sent home, and a few days afterwards he went to his father’s bedroom, packed up his father’s shirts, brushes, razors, etc., in a gladstone bag, and sold the lot to a man in the street for five shillings. A man of good social position and respectable ability, the colonel commanding a crack regiment, frequented low pot-houses, where he boozed with private soldiers of the lowest class, gave away his watch and chain and jewellery, and became filthy in person and swarming with vermin. A private soldier, on being reprimanded on parade by a commissioned officer for some trifling untidiness, smacked this officer in the face, and even when in prison, could not be got to see the matter in any other light than that of a good joke.

“These are cases of true ‘moral insanity’, but what are we to say of the frequent cases in which women of ample means and good social position steal from drapers’ shops? A small proportion of these are no doubt cases of moral insanity, but the majority of them are ordinary thieves, who presume upon their social standing and respectability to avert suspicion in the first place, and in the second to carry them scatheless if they happen to be discovered. Such women are not usually discovered to be thieves until they have continued the practice for some time and become bold from immunity. They execute their thefts with cunning and elaborate precautions, and when discovered they plead ‘kleptomania’, which, in such cases, means theft by the well-to-do.

“The consideration of moral perversion would not be complete without mention of the subject of perversion of the sexual instinct, about which such a redundant amount of literature has lately been produced. There is no doubt that there are abnormal beings of both sexes whose sexual inclinations are towards members, not of the opposite, but of their own sex, and these inclinations they gratify by various disgusting quasi-sexual proceedings. The fact being recognised, all has been said that need be said.”