This is the best introduction to the early history of Christian worship I have yet read. Jungmann begins with the earliest sources for Christian liturgy and proceeds to track the progress of developments in Christian worship practices up to the papacy of St. Gregory the Great. Jungmann takes a wide view, exploring both the Eastern and Western liturgical traditions, and includes a number of meditations and observations on Christian worship throughout.
Most of the first half of the book, which is concerned with the earliest sources on and of Christian liturgy, consists of an extended meditation on the meaning of Christian worship. Among the topics explored are the sources, both practical and theological, of church architecture, the contrast between pagan and Jewish worship on the one hand and Christian worship on the other, and the effects of early Christian heresies like Gnosticism on the liturgical developments of the early Church.
The second half of the book traces liturgical development from Constantine to Gregory the Great, a period during which the Christian Church, both East and West, was developing those liturgical traditions which have continued into the present day. His exploration of the effect of Arianism on the tenor and content of Eastern liturgy is a particularly fascinating portion of this study. The study of liturgy during this important period leads Jungmann into an exploration and explanation of the origins of elements of the modern liturgy, with a focus on the Roman Rite.
I recommend this book for anyone interested in the history and meaning of Christian liturgical practices as well as anyone with an intense interest in Church history more generally.