Book of Azaria is the title of the volume that collects the lessons, attributed to the angel Azaria, on the readings of festive Masses excluding the Gospel, which is mentioned there only with brief and sporadic references, having been fully illustrated in the work of ten volumes: The Gospel as Revealed to me.

Each lesson reported in this book was given from February 24, 1946 to February 2, 1947 on the same day as the Sunday or feast on which the respective Mass was celebrated according to the liturgical calendar of that time. In order to make the lessons usable regardless of liturgical reforms, the editor-curator has inserted, at the beginning of each lesson, biblical references according to the neo-vernacular and the texts of the prayers taken from a Missal that belonged to Maria Valtorta. With such references, which characterize the current second edition of the book, these are lessons of theology and spirituality that are valid at all times.

From a theological point of view, the lessons are accessible to every category of readers thanks to the clarity with which they expose the doctrinal concepts. Under the spiritual aspect, the lessons are given as a guidance to the writer and, in general, to people with charisms and to their directors.

The book was firstly published eleven years after the death of Maria Valtorta, who gave it the title of Angelic Masses (as lessons from an angel on the readings of Masses) and the subtitle of Directions (as spiritual directives for herself and for others who are on the same path of predilection and mission).

The title of Angelic Masses was considered misleading by Fr Corrado M. Berti, the Servite priest, professor of Sacramentary Theology, who collaborated with the publisher as the first editor of the Valtortian publications. He justified that title, if understood in the sense of an intertwining between the heavenly liturgy and the terrestrial liturgy, going so far as to quote the ancient Syro-Antiochian Eucharistic prayer, known as St. James, in which it is asserted that the priests, during the sacred rite, invoked the saints to offer with them the bloodless Sacrifice. But he feared that the title Angelic Masses could lead to suppose, instead, that the angels are priests and say Mass: a thought that does not reflect sound theology at all and does not agree with the doctrine expounded in the book in question. As for the subtitle: Directions, it was too general to make it clear that these are instructions and directives of a certain nature and intended for certain people.

The title Book of Azaria was chosen, among the various titles suggested, because of a biblical flavor and because it drew on the thought of Maria Valtorta, who had considered herself the writer of lessons received from her guardian angel: Azaria.