What binds us together as a nation? What do we hold in common? What are the invisible linkages of law, custom, trust—the “single garment of destiny,” as Dr. Martin Luther King, Jr., called it— which we weave with the intertwining threads of our lives?

In the late ’60s, Bob Dylan wrote a song called “I Pity the Poor Immigrant,” which channeled our nation’s dreams and images. And indeed, if you do some free associating with the word “immigrant,” you might conjure up some black-and-white images of “huddled masses” in steerage on the way to Ellis Island, or “coffin ships” creaking slowly across the Atlantic from famine-ravaged Ireland, or even African captives forced to endure the deadly Middle Passage. Or you might think of labor leader Cesar Chavez and the travails of migrant Mexicans workers in the late-20th century, or more recently, of the spate of laws and heated rhetoric that have been directed at undocumented Hispanic immigrants.