Writing's past tense, standing alone in the corpus — the word for what has already been set down.
Old English wrāt, the singular past tense of the strong verb writan (to write); one of the historic strong-verb classes, which is why write/wrote/written does not follow the regular -ed pattern most English verbs took.
The word's own past tense: the fact of something already committed to the page, which forgetting cannot undo. What was set down stays set down, however much changes after it.