"...Once upon a time, in ancient Egypt a slave forgot about cereal pap, which was earlier prepared by her for baking cakes and left in the sunlight.. Having noticed that the pap started to ferment in warmth, the girl got scared. Anyway, in order to avoid being blamed for waste, she baked the cake. During the baking, it turned out that the cake unexpectedly rose. This is the way how the sourdough was invented..."