Leaven represents fulfillment, a process which has gone its due course. The ultimate and supreme form of flour and water is a leavened loaf. Unleaven, on the other hand, is "not yet" what it aspires to be; it figuratively represents the beginning of a yet-unfulfilled process. It is presently immature and unripe. It is in the early stages of a journey.
My brother and I were talking about Pesach and the restriction of consuming leavened products. He told me that is was much more than just the instruction to eat matzah but wasn't sure about the details.
I always thought Pesach was about being slaves in Egypt and being freed etcetera. It turns out it has a lot more to do with mindfulness.
Whether the reason is because leaven represents the evil nature of humanity, a distancing from the natural order of things or a humbling to basics before reaching potential might actually be irrelevant.
A restriction on a food-type forces us to be more aware of what we consume and be mindful of the way we interact with the world around us.
While I am far from a religious person, I keep the dietary laws around Pesach every year and I'm somewhat strict about what I consume during these eight days.
It's difficult to explain to my friends why I hold on to this part of my religion when I don't keep kosher, I'm not shomer shabbat and I only go to synagogue on Rosh Hashanah and Yom Kippur.
All my reasons are introspective. They are about remembering from where I've come and also being aware of what I do. Pesach, for me, is partly about not consuming mindlessly but with thought and planning. It is about being aware of all the different ways I interact with the world and that freedom should not be equated with irresponsibility. It's about not taking freedoms for granted and to take a moment to reflect on who I am.
Everyone has their reasons and they don't have to be fixed for all time. These are mine right now. They may change. If you want to know more, let's discuss it over beers in a little over a week.