"Mother Joan of the Angels" is based on the infamous historical episode known as the Possession of Loudon. In the early 17th century in the French town of Loudon a number of nuns from a Ursuline convent were said to be possessed by demons and evil spirits. An investigation by the Church led to a local libertine Father Urbain Grandier being tortured and burnt at the stake. It was alleged that he had regularly been seen seducing and fornicating with the nuns. He was also accused of witchcraft by a demon who spoke through Mother Joan, the head of the convent. The ‘Possession of Loudon’ has inspired artists, writers and filmmakers over the last 100 years and a wide and varied body of work has built up around the episode, including Aldous Huxley’s "The Devils Of Loudon"(1952), John R. Whitting’s "The Devils"(1962), Penderecki’s "The Devils Of Loudon"(1969) and Ken Russell’s "The Devils" (1971). Jerzy Kawalerowicz’s "Mother Joan of the Angels" is not as well-known as a number of these works but fully deserves to stand alongside them.

At the time of filming, Jerzy Kawalerowicz was an experienced director with a body of work that stretched back for a decade and included films such as "Shadow" (1956) and "Night Train" (1959). In 1955 he had been appointed as artistic director at the 'Kadr', the production unit of the Polish Film School. Following the death of Stalin there had been an opportunity for directors to move away from the confines of the Kadr's social realism and to explore new perspectives. Making films alongside Kawalerowicz at this time were directors such as Andrzej Munk and Andrezj Wadja. This period is generally regarded as a Golden Age for post-war Polish cinema.

In the most celebrated analysis of the episode on which the film is based (The Possession at Loudon by Michel Certau)* the author describes how these events revealed the deepest fears of a society in flux and accelerated its transformation. He talks of a people torn between the decline of a centralized religious authority and the rise of science and reason, wracked by violent anxiety over what or whom to believe. Europe was drawing nearer and nearer to the Enlightenment, traditional and modern beliefs and science and religion were jockeying for position, clashing in a rapidly changing society. In what maybe a reference to the mirroring in the film, some contemporary commentators have remarked on how Mother Joan could be read as portraying the struggle of the Polish people being stuck between the rationalism of the communist state and the faith of the Church. There is also a school of thought that says that the film could be read today as an allegory for a Polish society that is still coming to terms with the anxieties and traumas of its transfer from communist state to a free-market capitalist system.

However the most telling commentary on the film is Jerzy Kawalerowicz’s own. For him it has a more intimate, universal meaning. He told Ray Privett of Kinoeye: "Matka Joanna od aniolów is a film against dogma. That is the universal message of the film. It is a love story about a man and a woman who wear church clothes, and whose religion does not allow them to love each other. They often talk about and teach about love – how to love God, how to love each other – and yet they cannot have the love of a man and a woman because of their religion. This dogma is itself inhuman. The devils that possess these characters are the external manifestations of their repressed love. The devils are like sins, opposite to their human nature. It is like the devils give the man and woman an excuse for their human love. Because of that excuse, they are able to love.” Allegory, metaphors and such like aside, the one thing that has not been remarked on in the little that has been written about this wonderful film is just how beautifully strange it is.