The book did have extraneous content such as when David meets a catechist.
Canon 18 of the Code of 1870 recognizes the offices of catechist, reader and sub-deacon (Wirzmann, The English Church and People in South Africa, p. 223 et seq.).
At the latter is a Church of England mission station under a native Indian catechist attached to the diocese of Rangoon.
Augustine's treatise was written at the request of a catechist, named Deogratias, who had asked him for advice.
As catechist at his college he read lectures on the Decalogue, which, both on their delivery and on their publication (in 1630), created much interest.