Jo's power base was concentrated in four offices: Inspector General's Office (사헌부; whose main function was to impeach corrupt or unprincipled government officials in court and local administration), Office of Censors (사간원; whose role was to criticize wrong policies of the king or ministers), Hongmoongwan (홍문관; an advisory council that answered the king's questions and educated the king with history and Confucian philosophy), and Royal Secretariat (승정원; which served as liaison between the king and ministries). The first three offices were collectively called Three Offices, or Samsa (삼사), as they provided checks and balance on the power of the king and the ministers and also served as organ of press that influenced general opinion of the court.