Teresa of Avila's Interior Castle, Room by Room

Teresa of Avila's image is a castle made of one diamond or of very clear crystal, containing many rooms, arranged around a centre. The soul is the castle. The door is prayer. You move inward, and the seven groups of rooms are seven stages.

The short version, in order. First: you get in at all, and the outer rooms still crawl with what she calls the reptiles that came in from outside. Second: you start hearing the call, and the pull backwards is strongest here. Third: an ordered, decent, disciplined life, and the trap nobody warns about, which is settling in it. Fourth: the hinge, where what you produce and what you receive stop being the same thing. Fifth: the prayer of union, and the silkworm. Sixth: the long, messy one, with raptures, voices, visions and heavy trials, and it is longer than any other section by far. Seventh: what she calls spiritual marriage, where her test of arrival is not the experience but the work that comes out of it.

Most summaries stop at the list. The list is the least useful part, because two of those rooms carry ideas that transfer out of the religious frame entirely.

She began on 2 June 1577, Trinity Sunday, and finished on the eve of St Andrew's Day, 29 November of the same year. Under six months, at sixty-two, while running a reform of her order and travelling constantly. She wrote it under obedience, which is to say her superiors told her to, and she says so.

It was not printed in her lifetime. She died in 1582; in 1586 the decision was taken to publish her works, the Augustinian friar and poet Luis de Leon was chosen as editor, and the book appeared in 1588.

She was canonised in 1622 and named a Doctor of the Church in 1970 by Paul VI, the first woman given that title. The dates matter for one reason: she is writing fast, to order, with no expectation of an editor, and it reads that way. The sentences run on, she loses her thread and says so, she apologises for her memory. That is not a flaw in the translation.

If you take one thing from this book, take this.

Teresa asks you to picture two basins that both fill with water. The first is fed from a distance, through pipes and waterworks, and you can hear it coming. The second is built at the spring itself, and fills silently, from below, with no machinery involved.

The piped water is devotion produced by meditation: you thought about something, you felt something, you worked for it and it arrived. The spring water is not produced. It rises, or it does not, and no technique reaches it. She is drawing a boundary, and she draws it precisely at the fourth room of seven, which means she puts the limit of method squarely in the middle of the path rather than at the end.

That is the transferable idea, and it survives losing every bit of theology attached to it. There is a class of interior state you can manufacture and a class you cannot, they feel different from the inside, and mistaking one for the other is the standard error in every practice that has a technique.

For the prayer of union she reaches for a working image, and it is worth the whole chapter.

Silkworms feed on mulberry leaves until they are full grown. Then they spin, out of their own mouths, a tight cocoon, and they bury themselves in it, and the fat ugly worm dies there. What comes out is a small white butterfly.

Her point is about the division of labour. Everything up to the cocoon is yours: the eating, the growing, the spinning. The house is built out of your own substance and by your own effort, and Teresa is explicit that this is where preparation goes as far as preparation can go. What happens inside the cocoon is not yours and cannot be scheduled.

She also does not stop at the pretty part. The butterfly comes out restless, unsatisfied with everything it used to like, and she treats that dissatisfaction as a sign of the real thing rather than a problem with it.

The sixth dwelling places are where visions, voices and raptures arrive, and where most readers stall, because it is enormous and it wanders. It is also where she does something almost nobody in the genre does, which is give you criteria for deciding that an experience is not real.

On visions: the genuine one arrives when the person was not thinking of seeing anything, with no idea of it having crossed the mind, and it appears entire and at once, producing fright and confusion that resolve into peace. Something assembled by the imagination does not behave that way. She also notes that an intellectual vision, unlike an imaginary one, does not pass off quickly but can last days and sometimes more than a year.

On voices: a divine locution is remembered word for word, and the hearer would notice a missing syllable. Fancy does not produce that distinctness. And on melancholy, her word for a bodily and mental condition rather than a spiritual state, she is blunt: its inventions arise and exist only in the imagination, whereas this comes from the interior of the soul.

Then she does the thing that separates her from most of her imitators. She sends the reader to someone else, and specifies the qualification: a confessor who is learned. Not the most devout available, not the one who agrees with you. Learned. She says it repeatedly and she plainly meant it, having been burned by directors who were pious and wrong.

The chronology is easy to miss and it changes how both books read.

Teresa was the senior figure. The reform of the Carmelite order was hers, and John of the Cross, twenty-seven years younger, joined it. In December 1577, the very year she wrote the Interior Castle, friars opposed to that reform seized John and shut him in a cell in Toledo for nine months. He came out with the poem that produced the phrase dark night of the soul.

So the two great texts of Spanish mysticism come out of the same year and the same institutional fight, from the two people on the same side of it. They also divide the labour: she maps the whole route and is best on the middle, he goes narrow and deep on the passage where the route stops working. Reading either alone gives you half.

Do not start at the beginning and grind forward, because the sixth dwelling places will stop you and they are eleven chapters long.

Read the fourth dwelling places first. It is short, it contains the two basins, and it is the part that stands on its own without any belief required.

Then the fifth, for the silkworm. Then, if you want the diagnostics, the sixth, and skim it rather than working through every chapter, because she is cataloguing phenomena and you can come back for the ones you need.

The Peers translation is out of copyright and complete online, chapter by chapter, which is what you want for a book you will read out of order. If you have Spanish, her prose is plain, ungrammatical and much funnier than any English version manages, and she is one of the few sixteenth-century writers who sounds like a person talking.