When you sell a man a book, says Roger Mifflin, protagonist of these classic bookselling novels, ‘you don’t sell him just twelve ounces of paper and ink and glue you sell him a whole new life.’ The new life the itinerant bookman delivers to Helen Mc Gill, the narrator of Parnassus on Wheels, provides the romantic comedy that drives the novel. Published in 1917, Morley’s first love letter to the traffic in books remains a transporting entertainment. Its sequel, The Haunted Bookshop, finds Mifflin and Mc Gill, now married, ensconced in Brooklyn. The novel’s rollicking plot provides ample doses of diversion, while allowing more room for Mifflin (and Morley) to expound on the intricacy of the bookseller’s art…