Quote Identification

Identify speaker, plot and significance.

When the "Jazz History of the World." was over, girls were putting their heads on men's shoulders in a puppyish, convivial way, girls were swooning backward playfully into men's arms, even into groups, knowing that someone would arrest their falls but no one swooned backward on Gatsby, and no French bob touched Gatsby's shoulder, and no singing quartets were formed with Gatsby's head for one link.