The saint wrote this luminous exposition of infused prayer in all its gradations and qualities, while she was suffering from a furious persecution.

And yet it breathes that heavenly calmness peculiar to spirits dwelling in the loftier regions of heavenly peace. Like all of her writings she composed this one under a very stringent obedience from her confessor, at that time Canon Velasquez, afterwards Archbishop of Compostella.

It is curiously allegorical in its framework; and yet the high topics are very plainly treated of, and they are made as intelligible to ordinary readers as is possible; all the more so, in fact, on account of the comparison she adopts between the stages of the soul's advancement in prayer, and the progress of a guest in a magnificent castle passing from its outer to its interior splendors.

The style is familiar, yet the tone is stately, often even majestic. The author sheds a clear light, clear though dazzling, on the vague and distant and ravishingly beautiful states of contemplative prayer.