Letters and diaries provide a personal angle on history and often give voice to the common person such as the WWI soldier in the trenches or the sweetheart on the homefront. Like all sources, letters and diaries follow the convention of their times and must be considered in light of the writer's motivations and biases. There are a number of published collections of letters especially those written by well-known historical figures (Walt Whitman or Winston Churchill).
To find published letters and diaries search the Story Library Catalog and use the terms diaries or correspondence in conjunction with your topic. For example:
Many sources for digitized letters and diaries are available online: