John of Salisbury was a 12th-century English philosopher and historian, known for his contributions to political theory and education. He was born around 1120 and became a prominent figure in the intellectual circles of his time, studying in Paris and later serving as a secretary to Thomas Becket, the Archbishop of Canterbury. His most famous work, "Policraticus," discusses the nature of authority and the role of the ruler in society. John emphasized the importance of reason and moral integrity in governance, influencing later thinkers in the fields of philosophy and political science.