A Tale of Two Cities (1859) is a historical novel by Charles Dickens; it is moreover a moral novel strongly concerned with themes of guilt, shame and patriotism. Dickens' primary source for this historical novel is Thomas Carlyle's The French Revolution. The narrative is extraordinarily dependent upon correspondence as a medium for ensuring the flow of events, and while not an epistolary novel in the way that Pierre Choderlos de la Clos' Les Liaisons Dangereuses is, nevertheless, it is immediately apparent that the flow of letters forms a driving center to much of the narrative development in this novel. The novel covers a period in history between 1775 and 1793, from the American Revolution until the middle period of the French Revolution.