John of Salisbury was a twelfth-century English author, diplomat, and bishop. He is known for his works on political theory, ethics, and education, and he was a prominent figure in the intellectual and political circles of his time. John of Salisbury's most famous work is "Policraticus," which discusses the nature of government and the responsibilities of rulers. He was also a close associate of Thomas Becket, the Archbishop of Canterbury, and played a role in the conflict between Becket and King Henry II of England. John of Salisbury's writings continue to be studied for their insights into medieval political thought and philosophy.