A Solid Introduction to the Mass And Its Spiritual Riches FATHER Guy Oury, a world-renowned liturgist, has written a solid introduction to the spirituality, history, and practice of the Mass. It is characterized by clarity of language and sound doctrine. This excellent book places the riches of the liturgical renewal within the grasp of all who read it. It can thus help them make the Mass the heart of their Christian lives.A Solid Introduction to the Mass and Its Spiritual Riches by Rev. Guy Oury.