In the Marian Institute in Würzburg, laborious days of constant prayer passed for Mother Frances. It seems like the industrious time of a fruitful gestation that would soon change the entire course of her existence. So it would be. 
A few months after the beginning of her new assignment in Würzburg, while she is working "with the visible blessing of the Lord", she experiences a very singular event.  One night, while she is in prayer before the Tabernacle, she hears the tolling of the bell of Himmelspforten, a Carmelite convent three kilometres away from the Marian Institute, in the Main Valley. At the same time she hears a voice telling her: "Go down  there!". She said to herself, “How can I do this in the middle of the night?” Then, as we read in Sr. Scholastica Demer's testimony, "suddenly she found herself in spirit  in the choir of the Carmelite sisters, singing and praying with them, and she heard the voice of St. Francis telling her: 'You shall learn to combine the active and the contemplative life. Enter the Carmel and remain there until another sign is given to you’ ". Indeed, later, the call to Carmel must have come to her in a clear and definite way, because in one of her notebooks she wrote, "August 4, 1880, Called to Carmel".