It isn't the feta necessarily. There are bacteria cultures naturally on the surface of all fruits and vegetables. That is why the fermenting books tell you you can just use some extra sea salt if you don't have any whey. The bacteria you need is already there.
My dad collected antiques, tools mostly. He did have a collection of redwing crocks, some were huge. He said the one gallon size were the hardest to find. The advertising on it makes it more special. I only have one it is a five gallon. It's nice that you still have use for something so old.