What is a prophecy and who is a prophet? Another way to ask this is, “what does God communicate to humans” and “who is able to receive this communication”? This lecture considers these questions and the vigorous debate surrounding them in the later Middle Ages. One new phenomenon was the emergence of non-elite laywomen who asserted that, though they lacked education or clerical training, they possessed secret knowledge of future events. Yet, such claims to prophecy, made independently of traditional authorities, elicited strong objections. Some male clerics questioned the legitimacy of lay prophets, even insisting that God would not speak to women. The clash between these positions had far-reaching repercussions, prompting reconsiderations of who could possess authority on spiritual matters, and the nature of humanity’s relationship with the divine.