" Luther envisioned a solution that was finally set out in the preface—now mostly ignored by many church historians—to his German Liturgy (or more specifically, The German Mass and Order of Divine Service). In this document Luther outlined the order of worship for three different kinds of worship services that he wanted the German church to embrace. The first service was the Latin Mass (Formula Missae), to be conducted in academic chapel settings so that students could become proficient in Latin and because so much of the Church’s rich hymnody was in Latin. The second service was also the Mass, but it was contemporized into vernacular German for the sake of the general public and cast in such a way as to make it accessible to the average layman. The third kind of service was neither for the “typical” Sunday congregation nor was it to be celebrated publicly. This service was for “mature” Christians who wanted to gather togethger privately in order to practice greater discipline and purer liturgy. "

― , Sacred House: What Do You Need for a Liturgical, Sacramental House Church?