This article explores the ritual functions of medical and mythical embryologies in Jewish ritual texts from late antiquity to the present. Together these sources tell three stories that show the development of participatory models of ritual efficacy. The first is the integration of medical embryologies into Jewish ritual practice. The second is that of a growing collaboration between human and divine in reproduction, and in prayer, through shared experience, shared embodiment and affect, and mutual mimesis that together constitute a powerful methexis. These in turn grant increased access to power. The third story is the growing maternalization of the divine, which in turn amplifies human-divine collaboration and inter-embodied participation in pregnancy. Thus from the period of late antiquity to early modernity, we see the ritualization of embryologies, remythologized to articulate an emerging theology of divine maternity and of inter-embodied human-divine participation in reproduction.