The term _catechismus_ (catechism), like its related terms, _catechesis, catechizari, catechumeni,_ was common in the ancient Church. In his _Glossarium,_ Du Cange defines it as "_institutio puerorum etiam recens natorum, ante quam baptizentur_--the instruction of children, also those recently born, before their baptism." The synonymous expression, _catechesis,_ he describes as "_institutio primorum fidei Christianae rudimentorum, de quibus kateceseis suas scripsit S. Cyrillus Jerusolymitanus_--instruction in the first rudiments of the Christian faith, about which St. Cyril of Jerusalem wrote his catechizations." (2, 222f.) Also Luther was acquainted with this usage in the ancient Church. He began his Catechism sermon of November 30, 1528, with the words: "These parts which you heard me recite the old Fathers called catechism, _i.e._, a sermon for children which children should know and all who desire to be Christians." (Weimar 30, 1, 57.) At first Luther seems to have employed the term but seldom; later on, however, especially after 1526, more frequently. Evidently he was bent on popularizing it. Between the Preface and the Decalog of the first Wittenberg book edition of the Small Catechism we find the title, "A Small Catechism or Christian Training--_Ein kleiner Katechismus oder christliche Zucht._" No doubt, Luther added the explanation "christliche Zucht" because the word catechism had not yet become current among the people. May 18, 1528, he began his sermon with the explanation: "_Catechismus dicitur instructio_ --Catechism is instruction"; likewise the sermon of September 14: "Catechism, _i.e._, an instruction or Christian teaching," the sermon of November 30: "Catechism, _i.e._, a sermon for children." In the Preface to his Small Catechism he again explains the term as "Christian doctrine." Thus Luther endeavored to familiarize the people with the word catechism.