Mother Teresa lived the latter part of her life in the global media glare. But the secrets of her soul remained invisible to all but a few. In the West a sentimental view of her took hold. Many regarded her as a wonderful little nun with a touchingly simple relationship with God. But this cosy consensus was shaken in 2007, when it was revealed that she had suffered a “dark night of the soul” for almost half a century.

Even those familiar with “dark nights” from the lives of the saints found it difficult to take this in. Mother Teresa was, at her death in 1997, arguably the most famous Catholic in the world. She had comforted thousands of “the poorest of the poor” in their last moments. She had founded the Missionaries of Charity, one of the world’s most dynamic new religious orders. She had even won the Nobel Peace Prize. And yet for 50 years she had felt a spiritual “darkness and dryness”.