Monsignor Guardini's book is first and foremost an introduction to prayer, but an introduction produced by a master. He anticipates the problems that will arise at every stage in the spiritual life, and encourages the beginner by showing him what promise is held out in the first steps of prayer, how to persevere and to develop in prayer life. Into this book, Monsignor Guardini has put his most mature thought and the reflections arising from a lifetime's study of the implications of faith. Yet it is all expressed in a manner intelligible to the uninitiated but attractive also to the more advanced thinkers.   The author brings out the role of Jesus Christ as the essential link in prayer, through whom alone we may know the Father, and he draws copiously on Scripture, throwing us back on what God Himself has said of our approach to Him. Prayer is seen, too, as a response to facts, meaning a grappling with the real world, which is a world created, sustained, and ordered by God. There are chapters on mysticism, on popular prayers, on the liturgy, all of which subjects are treated with new insight and a real understanding of the needs of all levels of spirituality.