In Les Liasons Dangereuses...

...Cecily de Volanges writes about hiding her love letters in her 'secretariat' under lock and key, which later in the novel her mother discovers, to her great dismay. I thought a secretariat could be perhaps a box in which to store documents, that one locks. Well, today I got my answer! I saw one that was contemporary to Laclos' writing of the novel. And it is a simply gorgeous piece of furniture!