CATECHESIS, in a general sense, denotes instruction given to any person in the first rudiments of an art or science, but more particularly of the Christian religion. In the ancient church catechesis was instruction given viva voce, either to children or adult heathens, preparatory to their receiving baptism. In this sense catechesis stands contradistinguished from mystagogica, which formed a higher kind of instruction given to those already initiated, and containing the mysteries of faith. The dispensers of such instruction are called catechists, and those who receive it catechumens.