Abstract
The disputes between Ambrose and Theodosius, the Carolingian rebellious episcopacy and Louis the Pious, and Gregory VII and Henry IV led to a same conclusion; the three emperors did penance. We can view these disputes as different episodes at different times of a same thing; the struggle between State and Church. First, it is necessary to replace these disputes in a broad historical context to show what their significance is. Then, we will look closer at these disputes in order to understand how public penance was used as a tool to assert Church's authority over kings. The relationship between Church and State is an important issue in the history of western Christendom. The conflict between Theodosius and Ambrose is generally seen as the first manifestation of the antagonism between the two authorities. Was the relationship between Church and State necessarily conflictive? It is clear that the Church and the State are two powers which both control or tend to control society. However, the idea of a separation between the spiritual power and the temporal power is enounced in the Gospels.
