By common consent, Alexis de Tocqueville’s Democracy in America, published in 1835, is the greatest work on the United States ever written by a foreign observer. To mark the bicentennial of Tocqueville’s birth, the Beinecke Library will hold a two-day international conference devoted to the French author on the weekend of September 30/October 1. The Beinecke exhibition “Tocqueville and Beaumont and the Challenge of Democracy” will remain on display at the library through October 24.