I write a lot of fantasy and most of it has a medieval setting. Because of this, I find that I have a lot of problems with similes and metaphors in my descriptions. You see, if I compare someone's stare to the glare of a laser, it makes sense to the modern audience, but might seem out of place because there was no laser's during medieval times. But if I compare a sound to the dripping of a clepsydra, that might make sense to someone who lived a long time ago, but will confuse a modern reader. They will have no idea what I am talking about. (Don't get all technical and hung up on my examples, please. I'm just trying to make a point.) Anyway, what I am asking is, whether it's more important that I make comparisons that make sense to a modern audience or comparisons that make sense to a medieval one? And what do I do if I'm struggling to find a comparison that's not cliche, but makes sense in both settings? Sometimes it seems impossible to do this. And is it okay to (rarely) use similes and metaphors that make sense to a modern reader and not an older one? Or is that never okay? Please back up what you have to say with reasonings. I am interested in discussing this since its such a re-occuring problem for me.