 These scholars have expanded the understanding of Lutheran orthodoxy to include topics such as preaching and catechesis, devotional literature, popular piety, religious ritual, music and hymnody, and the concerns of cultural and political historians.The most significant theologians of Orthodoxy can be said to be Martin Chemnitz and Johann Gerhard.Lutheran orthodoxy can also be reflected in such rulers as Ernst I, Duke of Saxe-Coburg-Altenburg and Gustavus Adolphus of Sweden.