Learning to Love Leaven: Lessons from Passover

It is almost Passover, and observant Jewish households will be getting ready for the Feast by ridding their houses of leaven, or chametz. I was long under the impression that this should be a fairly simple matter of discarding yeast, but when I learned more about the observance of Passover, the complex and fastidious processes for cleaning seemed to be more about ridding the household of flour, which confused me at first.

Baking with sourdough or natural yeast has given me a clearer instuitive sense of the reason for clearing the household of leaven. Although there are various complex instructions on the web for making sourdough, and exotic sources from which to aquire one, the most effective way is just from (real) flour. Some flours are so refined and otherwise challenged that they are less likely to retain traces of natural yeast, but stoneground whole wheat or rye is likely to yield a working sourdough if simply mixed with water (well - good water, anyway) and left to sit. Most households or at least communities in pre-industrial societies have maintained such leavens over many years, using and refreshing them in an unending cycle, just from flour and water.

This capacity of real flour to generate leaven is the basis of the need for eradication of chametz at Passover; it is not yeast (which after all does its work in the festive wine as well as the forbidden bread) that has to go, but active leaven or dough, which is flour with yeast at work in it.

The origins of this avoidance of leaven are of course related to the story of the Exodus and the command to eat with haste (Exod 12). This connection is also hard to make for the baker who knows only instant dried yeast; my sourdough breads can take an afternoon or overnight to prove.

In broader perspective however the removal of leaven for a period has other potential meanings beyond reminiscence of the Exodus story. Like the Christian season of Lent which is linked to it, Passover involves a cycle of abstinence and renewal (although somewhat distinctively, Passover connects festivity with abstinence). Removing leaven can and has taken on various positive symbolic meanings over the centuries in Rabbinic and other Jewish reflection; but it is also a powerful and even moving thing that the bread-maker can, when the time of Unleavened bread is over, simply mix flour and water to find that the possibility of leaven, and the good that goes with it, comes again.