First published in Spanish in 1932, this 10-day devotion to the Holy Spirit has attracted many readers to a deeper appreciation and veneration of the Great Unknown. The author was a poor dressmaker who, in spite of her very limited education, testified to an extraordinary understanding of the power and gifts of the Holy Spirit through her habitual and silent practice of heroic virtue.

One admirer wrote that this work leads even the most learned theologian to acknowledge the healthy and profound doctrine expounded. Yet it becomes clear from reading that the book is not written by a theologian but by a soul who has first-hand experience in the school of the Divine Spirit.