From the 12th century the court developed into a central institution of royal and princely rule. It was a “decision-making center and theater of power, consumer and entertainment center, distribution center, broker's seat for and for power, money and goods and social opportunities, for tastes, ideas and fashions of all kinds”. Medieval kingship was exercised in an empire without a capital through outpatient rulership practice. Philip had to go through the kingdom and thereby give his rule validity and authority. The greats of the empire gathered for deliberations on the court days. For Philip's reign, 28 "Hoftag" are known, of which only 12 took place within the Hohenstaufen sphere of influence. Somewhat more than 630 people can be found at Philip's court between 1198 and 1208, of whom around 100 belonged to the King's inner court, being "attested in a somewhat more noticeable density in the Hohenstaufen circle". The Bishops Konrad of Hildesheim, Hartwig of Eichstätt and Konrad IV of Regensburg and especially Konrad of Speyer joined to Philip's court. By contrast, none of the secular princes is as closely and frequently attested to at court as Bishop Konrad of Speyer. Duke Bernhard of Saxony, Duke Louis I of Bavaria and Margrave Theodoric I of Meissen probably had the most intensive contact within the court. They had profited significantly from the fall of Henry the Lion and feared that his son Otto IV would gain access to the Welf inheritance. The "Ministerialis" had in Henry of Kalden their most outstanding representant: he was not only a military leader, but also influenced Philip's politics by arranging a personal encounter with Otto. He is mentioned in more than 30 charters and also in narrative sources.