What are the *oldest* spicy books you know of that are commonly found on Libby?

I've been reading some historical romance and it's been great, but the characters are often mentioning their own "inappropriate" reading material, and now I just really want to know what that's like!

I want to get into the heads of people back then, see the mindset toward sex and roles and body parts. I'm curious.

But I also haven't read any "bodice rippers" from our mothers' and grandmothers' younger days, so if you've got recs there, I'd love to explore those, too.

I have several library cards, but I do mostly rely on Libby for ease of sending to my Kindle. However, if you know the perfect book that Libby probably won't have, I'd still like to hear about it (I'll cruise eBay or something lol)

Thanks for any and all suggestions!