§ 3.  Arrangement.  The Lectures of S. Cyril have a peculiar value as being the first and only complete example of the course of instruction given in the early centuries to Candidates seeking admission to the full privileges of the Christian Church.  “The Great Catechetical Oration” of Gregory of Nyssa is addressed not to the learner but to the teacher, in accordance with the opening statement of the Prologue, that “The presiding ministers of the mystery of godliness have need of a system in their instructions, in order that the Church may be replenished by the accession of such as should be saved, through the teaching of the word of Faith being brought home to the hearing of unbelievers.”  As an instruction to the Catechist how he should refute the opponents of Christianity, it is an apologetic work rather than a Catechism.  S. Augustine’s treatise De catechizandis rudibus is also addressed to the teacher, being an answer to Deogratias, a Deacon of Carthage, who on being appointed Catechist had written to Augustine for advice as to the best method of discharging the office.  S. Augustine’s Sermons De traditione Symboli, and De redditione Symboli, are not a connected series, but single addresses to Catechumens consisting of brief comments on a few chief articles of the Creed.  Cyril’s Lectures thus remain unique in character.