AFTER THE FLOOD: Inside Bob Dylan’s Memory Palace by Robert Polito (Liveright. 360 pp., $31.99) On Page 76 of the 1959 Hibbing, Minnesota, high school yearbook, a certain member of the senior class is quoted as vowing "to join ‘Little Richard’" after graduation. That didn’t happen. Once this music prodigy changed his last name to that of a dead Welsh poet, young Bobby Zimmerman became — and is still becoming — one of the most inventive, prolific and enduring artists of our (or any) time.