Ante-Nicene Fathers, Vol VIII:
Pseudo-Clementine Literature.: Chapter XIII

Chapter XIII.—Duties of Catechists.

“Let the catechists instruct, being first instructed; for it is a work relating to the souls of men.  For the teacher of the word must accommodate himself to the various judgments of the learners.  The catechists must therefore be learned, and unblameable, of much experience, and approved, as you will know that Clement is, who is to be your instructor after me.  For it were too much for me now to go into details.  However, if ye be of one mind, you shall be able to reach the haven of rest, where is the peaceful city of the great King.