Every bindery kept one perfect copy to measure the rest against. Our oxblood volume plays that role in every frame.
A reference you can see. The master volume is the standard: same size, same oxblood cloth, same dark ribbon in every sitting. When the reference object never changes, differences between portraits become purely about the sitter — hair, expression, wardrobe — which is exactly what a gallery should compare.
It also keeps generations honest. If a render changes the book — opens it, prints on it, gilds a title onto its cover — it has broken the reference, and we generate again. A master copy with writing on it would be a different, lesser book.
Keeping your own reference prop. If you build a series, pick one object and freeze it in your brief: same words, same position, every time. Models are good at holding a described object steady across a session; they drift when the description drifts.
Write the prop sentence once and reuse it verbatim. Treat it like the binder treats the master: measured, unaltered, and never improved on a whim.