Whereas government or court records are created by a central organization for specific purposes, and newspapers are created as public and commercial enterprises, diaries, journals and reminiscences are private documents created for a variety of purposes. Typically, however, most people never imagined that their personal diaries or journals would end up in an archive, being read by numerous historians!
Although many such personal documents were likely created during the late nineteenth century, few of them survive in a form that is useful and accessible to the historian. For unlike government and judicial records, diaries and journals were not typically carefully organized and preserved in public archives created for that purpose. Instead, these documents tend to end up in public archives in a haphazard and piecemeal way. Diaries and journals of the wealthy and privileged are over-represented. Many of the ‘common people' would not consider their personal lives to be of interest to the public, while others would not allow their personal writings to be available for public scrutiny. In addition, in some cases family members have “edited” diaries and journals before donating them to archives.
Regardless, sources like diaries, journals and personal reminiscences are very valuable because they provide us with information about life in earlier times from a personal perspective. They allow us to see beyond the government's purview, beyond generalized opinions and typical experiences into the unique lives of individuals. For instance, postmaster William Porte’s journals on the events in London and Lucan help us understand the social environment of those locales.
The varied, personal and unsystematic nature of the documentation journals and diaries provide constitutes their weakness as well as their strength as historical ‘evidence.' Often the writer will try and make him/herself appear in a better light or they will exaggerate to add interest to their journals or diaries. Their unique content reminds the historian of the variability of human experience, but it sometimes also inhibits our ability to make comparisons, or to draw conclusions relevant to the wider society.