You could say Parnassus has books in its blood, and not just because it’s owned by a novelist and a publishing veteran. Many of the people connected to this store have been working in the book business for years. Case in point: For the past four holiday seasons, we’ve been joined in December by expert bookseller Karen Davis. That’s Davis as in Davis-Kidd Booksellers, the independent retailer known to Tennessee book lovers for decades. Davis created a piece of Nashville history, and having her with us at this time of year reminds us that we are part of a long bookselling heritage.