Don't forget to study the addressee's history, too. In this case, Dr. John Nichols of Kirtland, Ohio. According to this list of documents available at Case Western Reserve University, it sounds as if it would be an interesting read:
John Nichols was superintendent of Western Reserve Teachers' Seminary, Kirtland, Ohio from 1847-1853. Charles C. Merrill resided in Kirtland and Chardon, Ohio and was an associate of Nichols' during the latter's superintendency. Collection consists of correspondence and other papers of the families of John Nichols and his associate, Charles C. Merrill. Includes letters (1840-1848) to Nathan Daggett, postmaster at Kirtland, and other papers relating to postal service there, including a petition addressed to United States Postmaster Francis Granger requesting the removal of Kirtland's incumbent postmaster, undated.