Of course there are many gradations between these two positions. Zwingli, the Zürich reformer, was of a different type from Calvin, while he was even more opposed to Luther than was the Genevan. Luther's rule was to abolish whatsoever was contrary to the Bible. Zwingli would permit only what was based upon or commanded by the Bible; he objected to the use of an organ, to the keeping of festival days except Sunday, and so on. Luther even tolerated pictures in the church. He was sure that no one would adore them if pervaded by the true spirit of the gospel, and he was convinced that this spirit could be successfully inculcated by means of preaching. Zwingli and Calvin both did away with all pictures in the churches. They had the walls whitewashed and the ten commandments and other passages from the Bible painted on them. Nothing is so characteristic of this difference between the Lutheran and the Calvinistic feeling as the history of an epitaph in an East Prussian church, the monument of the noble family of the earls of Dohna. At the time of the Reformation they joined the Grand Master, later Duke, Albrecht of Brandenburg in taking Luther's part. The epitaph, which was erected in the church of Mohrungen on the death of Earl Peter in 1553, was decorated with a picture showing the holy Trinity adored by the family of the donor. At the beginning of the seventeenth century the family went over to Calvinism, and the painting was altered by covering the image of the holy Trinity with black varnish and putting over it some Bible verses in gold letters. The different attitude toward the Bible finds its expression also in the fact that the Lutherans used hymns, whereas the Calvinists adhered to the Biblical Psalter. Of course the vigorous songs composed by Luther are most of them based upon Psalms and other Biblical passages, and so were the greater number of hymns in the Lutheran church. On the other hand, the Calvinists did not agree with the English church in taking over the alternative recitation of the Psalter from the mediæval exercises of the monasteries and large cathedral choirs. They used the Psalter in a rhythmical paraphrase adapted to modern singing, but keeping so near to the wording of the Psalms that they even called it the Psalm-book. The difference was, in fact, slight, but they felt it to be essential. The Lutherans followed the usage of the church, the Calvinists the very word of the Bible. It is remarkable, however, that hymns gradually gained more importance among the Calvinists, especially since the time of the eighteenth-century revivals, and that nowadays the hymn-book, enriched by the contributions of recent time from poets of all denominations, is in favour with all Protestants and in some circles is even in danger of becoming a substitute for the Bible.