Bread have a special taste or texture. At one time, all yeast-leavened breads were sourdoughs. Recently there has been a revival of sourdough bread in artisan bakeries. Traditionally, peasant families throughout Europe baked on a fixed schedule, perhaps once a week. The starter was saved from the previous week's dough. The starter was mixed with the new ingredients, the dough was left to rise, and then a piece of it was saved (to be the starter for next week's bread). The rapid expansion of steam produced during baking leavens the bread, which is as simple as it is unpredictable. Steam-leavening is
Substance theory and consistency to our ideas". Substance, overall, has two sets of qualities that define it, and how we perceive it. These qualities rush to our minds which must organize them. As a result, it creates a substratum for each object to which it groups related qualities. Two irreducible concepts encountered in substance theory are the "bare particular" and "inherence". In substance theory, a bare particular of an object is the element without which the object would not exist, that is, its substance, which exists independently from its properties, even if it is impossible for it to lack properties entirely. It