Complex sentence: Horace Mann (May 4,1796August 2,1859) was an American educational reformer and Whig politician dedicated to promoting the speedy modernization of U.S. society; he served in the Massachusetts State legislature (1827--37).
Split into simpler sentences: Horace Mann (May 4,1796August 2,1859) was an American politician and educational reformer. A Whig devoted to promoting speedy modernization, he served in the Massachusetts State legislature (1827--37).