Jules Massenet (1842-1912) and Pyotr Il'ych Tchaikovsky (1840-93) were almost exact contemporaries, and their operas Werther and The Queen of Spades were first performed in 1892 and 1890 respectively. Apparently the composers met only once, after an all-Tchaikovsky programme conducted by Édouard Colonne in Paris in 1889; but Massenet would probably have taken the opportunity to get to know the scores of a highly regarded Russian contemporary who recognised that they had something in common musically. However, the works’ respective protagonists, Werther and Hermann, are linked here, not because of the composers’ strikingly similar musical language, but because they show a comparable pattern of behaviour. Both fall instantly and desperately in love with a woman who is already engaged. They are in the grip of an idealised, unrealistic and destructive infatuation. When they declare that if their love is not reciprocated they will kill themselves, they mean what they say: Werther cannot accept a life without Charlotte and shoots himself; Hermann gains Liza's love only to abandon her for gambling – and when he loses at the table he too shoots himself.

Doomed love and suicide are common enough in opera, and with their romantically-charged music these two works vividly portray their protagonists’ emotional instability, immaturity and vulnerability. The two lurch from passion to despair, from yearning to anger, from suffering to suicide. It is only when they are dying that they find peace and crave forgiveness. Although they evoke frustration as well as sympathy, they are easier to identify with than Wozzeck and Grimes: as attractive, sensitive individuals who sing beautiful arias, it is no surprise that they can win the love of Charlotte and Liza respectively. We, too, can recognise something of ourselves, or people we know, in their experience. But their behaviour is hardly normal. Indeed, from a psychiatric point of view it is consistent with what is now called the emotionally unstable or borderline type of personality disorder.

‘Borderline’ describes people who show a marked emotional instability, with short-lived bouts of anger, depression and anxiety: they self-harm, threaten and attempt suicide. The term, though, has been used in different ways at different times and can hence lead to confusion. In psychiatry, it used to refer to the hinterland between neurosis – meaning depression, anxiety, phobic and obsessional states – and psychosis.