1. Converts were admitted into the Church after a process of oral instruction of more or less duration; for I am not here concerned with the extent of that duration, but with the fact that such instruction was invariably given by word of mouth, not by placing a book in the hands of those who came to be taught. What the Christian doctrine was it belonged to its teachers to say, and the system by which it was learnt was termed catechesis, _i.e._, instruction by word of mouth, by question and answer. This is the word applied by St. Luke in the beginning of his Gospel to Theophilus, to whom he addressed it; and the opening verses of the Gospel describe the thing itself with an accuracy which leaves nothing to be desired; for the Evangelist speaks "of the things that have been accomplished among us, according as they have _delivered_[146] them unto us, who from the beginning were eye-witnesses and ministers of the word;"[147] and adds, "It seemed good to me also, having diligently attained to all things from the beginning, to write to thee in order, most excellent Theophilus, that thou mayest know the verity of those things in which thou hast been instructed by word of mouth." By which we see that it was not a book which had been put into the hands of Theophilus to teach him Christian truth, but a doctrine delivered by personal teachers, and derived from those who were eye-witnesses, and administered to others what they knew. But after Theophilus had become a full Christian, a Gospel might be addressed to him for confirmation of his faith. The Church of which we know most as to its method of converting Gentiles is the Alexandrine Church, in which, from very early time, there was a famous catechetical school, founded, it is said, by St. Mark himself, the names of whose after teachers, Athenagoras, Pantænus, and still more Clement and Origen, have distinguished it.[148] Its method has been thus described:—