Seinfeld was a television marvel. Perhaps the most successful situation comedy series of all time, it ran from 1989 to 1998, and has become an omnipresent aspect of our lives as it continually runs in syndication and lives on in best-selling DVD box sets, making fortunes in the hundred millions for both of its co-creators. But there is yet another facet of Seinfeld at which we can marvel: the cast of characters on the show weirdly foreshadowed the rise to prominence of a large component of the dominant urban liberal wing of the Democratic Party. With a nod to Brian...