No clear date can be assigned to mark the divide between the medieval and the modern world. Many supposedly crucial markers of the new period, such as naturalism in art, can be found in the mid thirteenth century, and not only in Italy. Nevertheless, profound cultural, political and religious changes marking off the fifteenth and sixteenth centuries can scarcely be denied. Such changes were gradual and uneven, more complete in one place or area than in another, but those in the fifteenth and sixteenth centuries who sensed a decisive quickening in the pace of change were not wrong.

Perhaps the single most important change was the growth of the nation state, henceforth the framework for all forms of cultural and political development. Beginning in France, the rulers of Europe slowly gained control over internal enemies and secured their frontiers. In some countries, such as Germany and Italy, this happened regionally rather than nationally. This new political configuration was the salvation of Protestantism, which could have been crushed had the Catholic states acted together.