She accepts that being turned on or turned off is delicate alchemy, mysterious and necessarily beyond our understanding, and not only determined by what’s happening here in the room – by the shape of her body, for example, or whether or not he wants to fuck a pregnant woman – but determined by things that happened last week, or twenty years ago, or things that haven’t happened yet at all but which have tunnelled like time-travellers into the present moment and come into your bedroom and messed up your bed and said No sex for you today!

