There are thousands of people throughout history who have experienced a taste of a world outside of what we think we understand to be reality. Some have simply blown off that taste as a figment of their imagination; many others took it seriously and sought another taste. A few along the way were able to get their experiences and their thoughts regarding these experiences down on paper.
Over the past several years, I've spent a lot of time studying the Christian Mystics--Julian of Norwich, Teresa of Avila, John of the Cross, Anne Catherine Emmerich, Catherine of Siena, to name but a few. The mystics come from all walks of life. Some were from rich families, some from poor. Some could read four or five languages, some couldn't even read one. Some were avowed religious, some were not. Some of the mystics have founded orders; others have been declared doctors of the Church; still others have offered insight upon which dogma has been further understood and defined. Some have simply provided inspiration for those who have stumbled upon their work.
I guess I'm one of those "stumblers", having fallen into mystical theology while working at a Catholic book store. Interior Castle both fascinated and confused me. It's taken years for me to even begin to grasp what St. Teresa of Avila so clearly saw, and still light years lie between me and my full comprehension of those Castles she described.
In trying to understand what I first encountered in St. Teresa's masterpiece, I do a lot of stumbling along into various theologians, and more recently found this guy. I hope he gives you as much food for thought as he's given me.