Book Four serves as a transitional book for children moving from learning to read to reading to learn, as Elson put it. While earlier books in this series have stressed the mechanics of reading, Book Four shifts to applying those critical skills to reading for content. Book Four introduces children to stories of legendary heroes like Beowulf, Sigurd, and Roland and works from a diverse selection of great writers like Lewis Caroll; James Whitcomb Riley; Alfred, Lord Tennyson; and Henry David Thoreau; to name only a few. Book Four ends with a section devoted to Great American Authors including Benjamin Franklin, John Greenleaf Whittier, Henry Wadsworth Longfellow, and Nathaniel Hawthorne."