Irving created considerably more than fiction. He published biographies, notably a five-volume work on George Washington. He also wrote a biography of Christopher Columbus and was instrumental for perpetuating the illusion that Columbus' detractors feared: the globe was flat. His essays and stories are credited with inspiring Americans to love their country and help it grow. In addition to his history books, Irving is best known for his tales about the adventures of Rip Van Winkle and Ichabod Crane. These fictional characters became synonymous with New York City during the early 19th century when they were used on billboards to promote goods such as whiskey and cigars. Many other writers have been called "the father of" something or other, but it is difficult to compare one era's literary standards to those of another. For example, while it is true that Samuel Johnson was the father of English criticism, he could not be considered the father of American literature because there was no such thing in his time. However, by today's standards he is very weak compared to Henry David Thoreau or Walt Whitman. In fact, according to some critics, Irving is even below them in quality. It is clear that Washington Irving contributed to American literature by creating timeless stories that have inspired many people around the world. He showed Americans what they should value in life and helped them understand that there is no better place to live than America.