In their relations with foreign courts the Popes brought to bear every source of corruption and violence for the accomplishment of their ends. They availed themselves of the prestige attaching to their sacred office for the encouragement of insurrection and parricide. They openly sold the investitures of distant kingdoms. They armed the servant against his master, the vassal against his lord, the subject against his king. They prohibited the education of children as inimical to the interests of the clergy, who alone were declared worthy to enjoy the benefits of learning. When an obnoxious enemy was to be removed, they did not shrink from selecting instruments at whose employment honor and piety alike revolt,--the envenomed poniard, the sacramental elements mingled with deadly poisons and yet blessed by the ceremonies of the officiating prelate, whose instructions impressed the unsuspicious victim with the belief that he knelt in the very presence of God. According to Montaigne, the Holy Father was accustomed to use during the pontifical mass a contrivance which counteracted the effects of a consecrated draught which might otherwise be a messenger of death. From having been the vassals of the Emperor, the tributaries of the Saracen Emirs, and the tools of the Kings of France, the Popes in time arrogated to themselves imperial prerogatives; and his title to the crown was not considered as vested in a sovereign until it had been placed upon his brow by an ecclesiastic duly commissioned by the Successor of St. Peter. Through the insidious influence of a superstition, fostered by the ignorance of the time, the authority of powerful monarchs was disputed in their capitals. Degrading penances were imposed upon and performed by them without remonstrance. The humiliation of the prince in the eyes of his people increased, in a corresponding degree, the importance of the spiritual ruler who could inflict such punishments.