Parnassus on Wheels is Christopher Morley's first novel and a favorite among book enthusiasts. 

Helen McGill lives with her older brother, Andrew. Andrew is a former businessman, turned farmer, turned author. One day, Roger Mifflin, who travels around the New England countryside of 1915 with his book wagon named Parnassus on an itinerant mission of enlightenment, shows up on their farm. Mifflin's delight in books and authors is infectious. 

"When you sell a man a book," says Mifflin, "you don't sell him just twelve ounces of paper and ink and glue; you sell him a whole new life." 

Helen arranges to buy Parnassus, partly to prevent Andrew from buying it, but mostly to treat herself to a long-overdue adventure of her own. 

The prequel to a later novel (The Haunted Bookshop), and the first of two novels to be written from a woman's perspective, it offers a glimpse at a proto-feminist perspective from the early 1900s. Inspired by the novel The Friendly Road by David Grayson (pseudonym of Ray Stannard Baker), it starts with an open letter to Grayson, taking him to task for not concerning himself (except in passing) with his sister's opinion of and reaction to his adventure.