How Diaries Reveal an Era

An official document is created to establish something: to appoint someone, file a report, or grant permission. It contains the decision, but not the life surrounding it. A diary is written without any particular purpose, so it records things no one thought to write down.

One of the best-known examples is a 17th-century London official who kept a diary for himself and casually described the plague and the Great Fire from the inside: what it smelled like, where people ran, and what they managed to carry out. Official documents from the same year give figures and orders, but they cannot show what it felt like.

The last point is the trickiest. An author may avoid a subject out of fear, propriety, or because it is too ordinary to mention. You can tell which is the case only by comparing several diaries from the same period.

This source has a built-in bias. The people who wrote were those who knew how to write and had time to do it, while the diaries that survived were those whose descendants thought they were worth preserving. The voices of the illiterate majority have barely reached us.

The second bias lies in the genre itself. Many people kept diaries with an eye to a future reader and edited themselves as they went. Wartime entries often also went through censorship, and sometimes the author edited them years later, already knowing how it all turned out.

That is why a diary almost never stands alone in a historian's work. It is placed alongside parish registers, accounts, newspapers, and other diaries, and the truth emerges where they intersect. A single entry works as a detail, but not as proof.