Had it not been for her novel “The Crystal Cave”, I wonder if I’d ever have picked up Bulfinch’s Mythology, Beowulf, a bunch of other stuff. Oh, and had I not, I might have amounted to something, but nevertheless... ;^)
https://www.youtube.com/results?search_query=mary+stewart+crystal+cave
Only three books I can say that about. Fire Hunter and The Velvet Room are the other two.