The painting of Mary Undoer of Knots speaks to so many not just because it’s beautiful, but also because of its theological significance: the image contains many teachings and is a powerful guide to prayer.
The painting evokes a particular story. It was made as an ex-voto of gratitude to Mary for a grace obtained through her intercession in saving a struggling marriage from divorce (1). Therefore it acts as an “exemplum”: in literature, both sacred and secular, an exemplum is a lesson given in the form of a short story, a tale, a fable or a parable. It is part of the apologetics genre (2) and has a powerful argumentative force. In the Gospel, Jesus teaches through parables, which the listener must interpret to find their symbolic teachings. The exemplum thus has full argumentative value. Literature is full of fables, tales and other apologues whose purpose is to teach us from a story.
This is probably why this painting, with its exemplary value, touches those who contemplate it.
It is believed that Hieronymus Ambrosius Langenmantel worked with J. G. M. Schmidtner on the symbols he wanted to appear in the painting. We can see that the artist grounded his work in the Marian iconographic tradition, endowing it with a striking theological dimension.
Isabelle Rolland. Marie qui défait les nœuds. D’un “miracle conjugal” à une dévotion universelle (Mary Undoer of Knots: From a "marital miracle" to a universal devotion). MDN 2022
(1) See the story of the Langenmantel couple and the marital miracle that led to the devotion.
(2) The adjective "apologetic" is both a literary term for an argument based on apologue (fable, tale) and to a theological term for the rational defense of the faith.