Why do you want your only one to die, who as you know, loves you with soul and body, who sighs for you every hour at every moment, like a hungry little bird... as the turtle-dove, having lost its mate, perches forever on its little dried up branch, so I lament endlessly... you are the only woman I have chosen according to my heart.
That text is from a 12th Century letter from a woman to another lamenting their separation. What it bears testimony to is the reality of lesbian relationships going back into the medieval period. It is hard to read that text with its references to exclusivity or indeed to the mate of the turtle dove without thinking that it is, in some sense, a love letter. But it is not alone- Lesbian literature in some form was around during the entire Middle Ages- of course as Lesbianism was prohibited and women were the silent sex during the period, there isn't that much of it but individual examples are there which illustrate what may be a greater silent trend.
The canon lawyers definitely thought that that was true. As Christianity became the dominant religion of Europe, and as its believers became more literate they developed penitentials and other legalistic codes to describe sin and administer penitence. The Penitential of Theodore reccomended that a woman who indulged in vice with another women did penance for three years- more if she were married. The Penitential of Bede stated that a woman who used an instrument in sex with another woman should do an extra four years penitence. Hildegard of Bingen argued that Lesbians usurped the male role, both in sex and in general, Etiene de Fougeres suggested that Lesbians sometimes play the cock, sometimes the hen. The fear of Lesbians was the fear of mannish women.
On the other hand, Lesbianism did not get the attention that either male homosexuality or heterosexual adultery got. Perhaps it was less common. Perhaps as well it threatened the family unit less: adultery could end in a confusion about the legitimacy of children, crucial in a society like that of medieval Europe based around lines of descent. Furthermore contemporaries couldn't quite believe in sex without penetration- women were the passive receivers of sexual attention and aggression, not the instigators of it. Indeed one medieval text argued that a mannish woman turned in either of two ways- if filled with lust she became an active seductress, if totally bereft of human feeling, she became a Lesbian.
Women though were punished for being Lesbians- and practical steps were taken to dissuade Lesbianism. In 1568, a woman was drowned in Geneva for a 'detestable and unnatural' relationship that she had with another woman. In 1405 a French woman called Laurence appealed against a conviction for Lesbianism, insisting that her partner, Jehanne, had been the instigator of the crime. A lawyer in Seville in the 16th Century witnessed the flogging of several female prisoners convicted for making artificial sexual instruments to indulge with each other. In general the courts tended to leave Lesbianism alone though- for the reasons I gave above. Yet in other parts of medieval society we find that practical measures were taken against Lesbianism- with nunneries having strict rules about communal sleeping arrangements, prohibiting nuns (particularly old and young nuns) sharing beds and maintaining a light on at all times in the dormitory.
Such a description shouldn't lead us to think that medieval Lesbianism was in any way similar to modern Lesbianism- the letter I quoted from at the beggining is phrased within the conventions of courtly love poetry. To go further, medieval individuals often thought of themselves in wildly different ways to modern individuals. Take the case of Bernadetta Carlini, an Italian nun, who claimed to have visions and to be possessed by an angelic spirit. Carlini's spirit used her body to have sexual relations with another nun in her convent- she was sentenced to imprisonment. Historians like to quarrell over whether Carlini was what we would think of as a Lesbian- she said at her trial that she had no memory of her sexual escapades- in truth its a false question. The real answer is that she like many medieval men and women thought differently about their lives than we do- instead of as historians like to do, forcing them into modern straight jackets, its worth considering what they experienced.
The difficulty in this field though is that that isn't always that easy. Carlini's case is only there because she was tried and we have the transcript, we don't have much evidence to go on here. Much of what I have written comes from an article by Jacqueline Murray (within this collection), Murray attempts to make up with theory what she lacks with evidence, a parlous proposition for history which is an empirical approach to the world. Having said that, there definitely seem to have been medieval Lesbians- and looking at the way that both the Church and courts approached them reveals the deeply sexist orientation of medieval society. Women just couldn't be evil because they were recipients, not aggressors, in the world.
What it also reveals I think is that something about the subject of human nature- lesbianism is natural to human beings- but the forms, particularly the emotional forms it takes, change with societal change. That movement is a movement between artificial constructs to express a natural reality- Carlini's experience of Lesbianism was a different expression of an underlying emotion that she shares with Jodie Foster. They might say different things and feel different things- but the underlying thing they share is an attraction to women.