In honor of the first Democrat to win two terms as president since Franklin D. Roosevelt, members of many of the nation's past and present first families celebrated the life and political talents of Bill Clinton on Thursday as they dedicated his library here in a chilly, rain-drenched ceremony on the banks of the Arkansas River. "Welcome to my rainy library dedication," a hatless Mr. Clinton said somewhat wistfully to a crowd of 30,000, most of them hidden under umbrellas. Bucking himself up, he said his late mother would have reminded him that "rain is liquid sunshine." The ceremony, held...