In September 1965, Pope Paul VI issued the encyclical titled Mysterium Fidei (Mystery of Faith) to provide the faithful with the teachings of the Catholic Church on the doctrine and worship of the Holy Eucharist. The first half of Catechism on the Real Presence is an eloquent question-and-answer catechism that carefully details each of the main points of Mysterium Fidei, cross-referenced to specific paragraphs in the document itself. The latter half of the book contains the entire text of the encyclical itself as a convenient reference. Also included are notes which refer to various Bible readings, encyclicals, and the writings of the Church fathers. Finally, a topical index points the reader to both the related questions in the catechism and the paragraph in Mysterium Fidei.

Father Hardon's ability to take a difficult subject and explain it with directness and simplicity shines in this catechism. The very first question tells us why we should make time to study this topic in depth both for ourselves as the catechists of our children and for our children themselves. Question 1 asks, "What is the most precious treasure of the Catholic Church?" The answer is, "The most precious treasure of the Catholic Church is the Holy Eucharist, which is the most fundamental truth of the Catholic faith." This book is a valuable addition to a high school level apologetics or doctrine class, or to a Confirmation preparation course for older students.