Complex sentence: Sparks was one of the American intellectuals who received French author and traveler Alexis de Tocqueville during his 1831--1832 visit to the United States, his extensive conversations and subsequent correspondence informing de Tocqueville's best-known work "Democracy in America".
Split into simpler sentences: Sparks was one of the American intellectuals who received French author and traveler Alexis de Tocqueville during his 1831--1832 visit to the United States. Sparks's extensive conversations and subsequent correspondence informed de Tocqueville's best-known work, "Democracy in America".