The Large Catechism by Dr. Martin Luther

SHORT PREFACE OF DR. MARTIN LUTHER. This sermon is designed and undertaken that it might be an instruction for children and the simple-minded. Hence of old it was called in Greek catechism, i.e., instruction for children, what every Christian must needs know, so that he who does not know this could not be numbered with the Christians nor be admitted to any Sacrament, just as a mechanic who does not understand the rules and customs of his trade is expelled and considered incapable. Therefore we must have the young learn the parts which belong to the Catechism or instruction for children well and fluently and diligently exercise themselves in them and keep them occupied with them.