His famous twenty-three catechetical lectures (in Greek, ''Katecheseis''), which he delivered while still a [[presbyter]] in 347 or 348, contain instructions on the principal topics of Christian faith and practise, in rather a popular than a scientific manner, full of a warm pastoral love and care for the [[catechumenscatechumen]] s to whom they were delivered. Each lecture is based upon a text of [[Scripture]], and there is an abundance of Scriptural quotation throughout. After a general introduction, eighteen lectures follow for the ''competentes'', and the remaining five are addressed to the newly baptized, in preparation for the reception of [[Eucharist|Holy Communion]].

vigorous polemics against pagan, Jewish, and heretical errors. They are of great importance for the light which they throw on the method of instruction usual in that age, as well as upon the liturgical practises of the period, of which they give the fullest account extant.