Presidential Primaries: Where Did They Come From?

In 17 days, the state-by-state slog to the presidential nomination will finally begin for both Democrats and Republicans. Since 1952, the winner has been decided before the pageants both parties still euphemistically call their "nominating conventions." It's often said that the primaries have replaced "smoke filled rooms" with "the voice of the people." Is that really true? Are primaries the best way for divided political parties to choose their leaders?