I've seen a number of sourdough starter documents that recommend all sorts of procedures that reek of superstition and magic. Some use "yeast" from the air, some from grapes and I just read about one that uses pineapple and/or it's juice. With all the thousands (millions) of random bits of biological material floating around, why would this make a starter culture, instead of, for example athletes foot or some random mushroom spores from the front yard. "Creating a friendly environment for yeast" just doesn't seem like a very reliable or even safe method of producing a food ingredient. Is there something I'm missing here?