The word class — as in working class, middle class, upper class — was not used in the Renaissance to describe social division, but by the thirteenth century, and even more so by the fifteenth, the idea of a hierarchy based on wealth was emerging. This was particularly true in cities, where wealthy merchants oversaw vast trading empires, held positions of political power, and lived in splendor rivaling that enjoyed by the richest nobles. (See “Individuals in Society: Cosimo and Lorenzo de’ Medici.”)

The development of a hierarchy of wealth did not mean an end to the prominence of nobles, however, and even poorer nobles still had higher status than wealthy commoners. Thus wealthy Italian merchants enthusiastically bought noble titles and country villas in the fifteenth century, and wealthy English and Spanish merchants eagerly married their daughters and sons into often-impoverished noble families. The nobility maintained its status in most parts of Europe not by maintaining rigid boundaries, but by taking in and integrating the new social elite of wealth.