When sliced bread was first sold, it was marketed as "the greatest thing since..." what?

We've all heard the phrase "the greatest thing since sliced bread." Machine-sliced bread was first produced on a wide commercial scale on June 7, 1928 by the Chillicothe Baking Company in Missouri. The CBC marketed their new Kleen Maid Sliced Bread using a variation on the now-familiar axiom, touting sliced bread as the best thing since another bread-related innovation.

When sliced bread was first sold, it was marketed as "the greatest thing since..." what?