The apprenticeship years of the author of "Tom Sawyer." For four and a half years, Mark Twain learned the perilous profession of a riverboat pilot on the Mississippi. The autobiographical account of the great storyteller captures the colorful, adventurous activity on the vast river, offering grandly comedic scenes as well as a wealth of images of striking and peculiar character types from the vigorous America around the mid-19th century. "Literature is an art, not an inspiration. It is, so to speak, a craft that must be learned - one cannot simply 'pick it up.' It cannot be learned in a year or in five years. Its capital is experience." Mark Twain, in a letter from 1885.