This book is based on a series of sermons delivered by Ronald Knox to students at a convent school during World War II. Its purpose is to help Catholics, both new and old, understand the deeper meaning and spirituality of each movement, prayer, and ritual in the Mass. Knox breaks down the liturgy (which at that time was the Tridentine Rite or traditional Latin Mass) into small parts and reflects on their meaning, as if the Mass were viewed in ' slow motion.' With simple yet engaging language, he connects the seemingly ordinary elements of the Mass with profound spiritual truths, helping the faithful to participate more consciously and reverently in the Eucharistic celebration. Although written based on the old form of the Mass, his reflections remain relevant and useful for those who wish to deepen their understanding of the current Mass.