Old diaries from your ancestors

Does anyone have old diaries from their ancestors? (I’m talking written records of anyone who was not alive when you were born.) I’m curious how old they are, what language they’re in, and if they’re legible? I want to start keeping a written journal (including the banalities of my life) as I would have loved to have something like that from my great-grandmother or older. My suspicion is that a diary more than 100 years old probably becomes something very unrelatable, either because the nature of the language changes, the humor changes, or the things people value or lament change. Curious what others’ experiences are.