The Invisible Line: Daniel Sharfstein, a Vanderbilt law professor visiting Baltimore for an engagement at the Enoch Pratt Free Library, followed three families, from the Revolutionary Era up to the Civil Rights movement, as they straddled the color line and changed their racial identification from black to white. While previous stories of "passing" have focused on individuals' struggles to redefine themselves, Sharfstein's subjects managed to defy the legal definitions of race within their own communities.