First, in the Middle Ages, there has been two major poles of power, the King and the nobles. The Magna Carta, for example, limited the power of the king with respect especially to the nobility. The rising merchant class has growing wealth, and became a third nexus of power. The middle class tended to be strongly Calvinist and Puritan, and opposed to the Episcopal form of church governance which tended to concentrate spiritual authority in bishops appointed from the aristocracy. They were generally very strongly opposed to Roman Catholicism (or "popery") and luxury, following Calvinist notions of attempting to create pious cities (on the model of Calvin's Geneva) by legislating morality.