I know I read the account of a Greek woman talking about how her grandma made yogurt by leaving the warm milk uncovered on the counter for a while and then covering it with a thick blanket to stay warm and culture - the yogurt cultures must literally be in the air in that area of the world. I've also heard the bacillus bacteria is in soil and can be found in high concentrations in the little balls of soil around ant hills. That's on my mental list to try since I now know from experience all you get from leaving warm milk out around here is sour milk.

Currently, I just use some of my previous batch to culture my current batch. But there's this niggling part of my brain wondering what would happen if my starter went bad and I couldn't buy more yogurt from the store...