People often tell you that the best books are written when the author is writing the book they most want to read. The flip side of that, is that not all of your potential readership is going to love the same things you do. But some will. And as long as the hidden "Easter eggs" can be read as background color, I see nothing wrong with tossing in a bit of geekery that only a subset of readers will fully appreciate. I suspect I hold this attitude in large part because I'm accustomed to SFF readers who are usually quite cheerful about swallowing worldbuilding on topics they aren't expected to be experts in.
I have regular scenes where my characters debate the logical and philosophical underpinnings of thamaturgical theory. Of course I don't expect the reader to understand it in detail, nor do I intend to have the characters sit down and explain it to them. The scenes serve the purpose of saying, "These are experts, interacting with each other at a no-holds-barred level, and your take-away is to appreciate the fact of their expertise, not to become an expert yourself." In a hard SF novel when the characters have an as-you-know-Bob discussion of how the warp drive functions, the point is that you're supposed to believe that those characters could build a warp drive, not that you should come out of it being able to build one yourself.
So, no, I don't actually expect any but a very few of my readers to be familiar with 15th centry Latin memorial inscription formulas or the ambiguities of how they might be expanded. But some day, when I write Tanfrit's story, I hope some of those few will think back to the following scene and say, "Ha! I wondered about that!"
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Chapter 10 - Margerit
There was a gate hanging crazily off its hinges that let them into the little yard. The door to the cottage itself was long since gone and the opening let in barely enough light to see the noisome remains of straw bedding. Margerit ducked back out quickly and examined the yard from within. The wall had been built from odds and ends of stone: smooth boulders tumbled by the river, small worked squares that must have been repurposed from some other source, a tall broad slab that stood the full height of the barrier and might well have determined its course. On second examination, the shape of that stone became familiar and she went to crouch before it and touch the traces of carving that still showed through the moss.
A sharp stick uncovered the edges of lettering and the shape of an escutcheon above, though the device on it was only recognizable as bearing birds of some sort. Barbara joined her, scraping gently at the moss to reveal the beginning of the inscription. HIC IACET…
“No surprise,” Margerit said. “I wonder what churchyard they pillaged for this?”
“The stone is set rather deeply. If I didn’t know better, I’d think it marked the original grave. Let’s see whose memory we’re meant to call to mind.”
They worked more carefully now, picking the dirt and vegetation out of the lettering. The end of the line held only a single name. Margerit’s heart began hammering as it came clear: TANNFRIDA.
Barbara laid a hand on her shoulder. “She wasn’t the only woman by that name. Don’t assume—”
But Margerit had attacked the obscuring moss more frantically. Why else had the mystery led her here if not for this? The drizzle started again, but she took no notice of anything except what the stone revealed. The Latin was clumsy and ambiguous, abbreviated to fit the stone and not the standard formulas of a churchyard monument.
HIC IACET TANNFRIDA
SUSANNA SOROR CARISS’ EIUS
“Doctora Universitatis Rotanaci,” Margerit breathed. “It must be. But…?” So many questions. Why here? Why did the dozzures at the university deny she had ever taught there? Tanfrit’s scholarship was legendary, even in the few scraps that survived. Why was she buried here in obscurity, commemorated only by Susanna, her most beloved sister?
“Why here?” she asked aloud.
Barbara offered a hand to help her rise. “You know what the legends say, that she was a suicide. They couldn’t have buried her in a churchyard.”
It wasn’t the question she’d meant to ask and the answer made no sense. “But those legends say she threw herself in the Rotein from a broken heart and was lost,” Margerit countered. “This isn’t lost.”
“It could be a cenotaph,” Barbara cautioned. “But no, not if it says iacet. And yet—”
They stared at each other in wonder, forgetting all the rest of the world around them. “This is it,” Margerit said abruptly.