Mass immigration from Mexico, legal and illegal, transformed California and created a fractured, riotous, and unstable polity.The sad news that Brian Wilson, the musical genius behind the Beach Boys, died last week at 82 carried with it a strange and foreboding symbolism. His death came as Los Angeles was reeling from a series of riots — and poised to plunge into a period of sustained civic unrest.The immediate cause of the unrest is violent opposition to the legitimate enforcement of federal immigration law, especially among Mexican nationals and Mexican-American residents of Los Angeles. In recent days we’ve all heard impassioned...