A Power Governments Cannot Suppress
"The war in Mexico intensified the bitter controversy already simmering in the United States over slavery. Ralph Waldo Emerson had predicted that, 'The United States will conquer Mexico but it will be as the man swallows the arsenic, which brings him down in turn. Mexico will poison us.' Commenting on Emerson's warning, the civil war historian James MacPherson has written: 'He was right, the poison was slavery.' "