Who Am I?

I was born in 1794 in Dorchester Massechusetts, and I died in 1865. I graduated from Harvard College at seventeen, and was known for being a brilliant writer. I was a pastor, and was known for my eloquent preaching. In 1814 I was elected Professor of Greek Literature in my Alma Mater. I was elected to Congress, and held that seat for ten years. I was the Govenor of Massechusetts for 4 years, and I was appointed Minister to England. I was also the President of Harvard University and the Secretary of State. I helped buy back Mt. Vernon with the proceeds from a lecture that I wrote. Who am I?