The slave narratives were integral to African-American literature. Some 6,000 former slaves from North America and the Caribbean wrote accounts of their lives, with about 150 of these published as separate books or pamphlets. Slave narratives can be broadly categorized into three distinct forms: tales of religious redemption, tales to inspire the abolitionist struggle, and tales of progress. The tales written to inspire the abolitionist struggle are the most famous because they tend to have a strong autobiographical motif. Many of them are now recognized as the most literary of all 19th-century writings by African Americans, with two of the best-known being Frederick Douglass's autobiography and "Incidents in the Life of a Slave Girl" by Harriet Jacobs (1861).