Two for the price of one this week, and it could have been four.
 
In the mid- to late-1200s, the Convent at Helfta (Germany) had four of the most influential mystic theologians, "the glory of German monasticism" (ewtn.com/catholicism/library). All four were there together for at least a few years in the 1280s–two were named Gertrude and two, Mechtilde. Though they all seemed to help each other grow in spirituality, the two most prominent were Mechtilde of Hackeborn and Gertrude the Great.