After the Procatechesis, which is simply an introductory exhortation to the newly admitted Candidates, he devotes three Lectures to the need of a sincere purpose of mind, the efficacy of repentance, and the general nature and importance of Baptism.  The fourth Lecture gives “a short summary of necessary doctrines,” stating with admirable clearness and brevity ten chief points of the Faith, and the arguments on each point, which are to be developed in the remaining Catechetical Lectures v.–xviii.  He thus traverses the whole ground of Theology as expressed in the Creed of Jerusalem, of which the exact language is given in the titles of the successive Lectures.  These instructions to the ‘Illuminandi’ (φωτιζομένων) were followed on Easter-day by the administration of Baptism, Chrism, and Holy Communion:  and on the following days of Easter-week the ceremonies and doctrines proper to each of these Sacraments were explained in the five Lectures on the Mysteries (Μυσταγωγίαι) to the newly-baptized (πρὸς τοὺς Νεοφωτίστους).  These Mystagogic Lectures thus form a most important record of the Sacramental Rites and Doctrines of the Eastern Church in the fourth Century, the most critical period of Ecclesiastical History.