How does studying an intellectual movement like Romanticism offer insights into other aspects of American history and society that extend well beyond the intellectual trends of an era?

Source : America:The Essential Learning Edition. How does studying an intellectual movement like Romanticism offer insights into other aspects of American history and society that extend well beyond the intellectual trends of an era? One author in particular, Henry David Thoreau, had a lasting impact on American society. Examine how his work influenced the Civil Rights Movement of the 1960s? (you can use your own opinion)