In the midst of writing a 13-page analysis of a complex area of Jewish law, Rabbi Xava De Cordova found something she wasn’t expecting to see in the medieval-era sources: flexibility. De Cordova is transgender and had long wondered whether she could feel a sense of belonging while studying reams of rabbinic writings on halacha, or Jewish law, which stretch back thousands of years and often prescribe different practices for men and women. The laws of ritual purity, for example, prescribe specific behaviors for women on the assumption that they all menstruate. Trans women do not. De Cordova said that gap and others had her thinking, “I don’t really know if I can find a place for myself in this literature.”