Philip Stanhope, 4th Earl of Chesterfield
In politics, he is best known for the time he was Lord Lieutenant of Ireland. As a writer, he is best known for his Letters to his Son. Those letters were not really written to be read by the general public. His widow Eugenia Stanhope first published them in 1774. Letters to his Godson was published in 1890. Both sets of letters are written with great style and knowledge.