Every Erev Pesach, something fascinating happens in frum homes across the world. Perfectly rational, learned, sensible people, people who can navigate a sugya in Bava Kamma or lehavdil analyze a spreadsheet, suddenly find themselves on their hands and knees, peering into crevices they haven’t thought about since last Pesach.

Their wives are even more frantic. They are looking for chometz. Tiny chometz. Invisible chometz. Chometz that is, in all likelihood, pachos m’kezayis, botul, and halachically irrelevant. And yet they cannot stop looking.

All the lomdus in the world and all the rationale won’t negate their quest to rid themselves of those tiny little particles. I used to wonder if General Mills invented the Cheerio just to have something that rolls under a refrigerator, forcing the puniest of men to suddenly become supermen in their mission to move mountains to rid themselves of even the tiniest “O.”

I recently heard a shiur in Menachos from Reb Sruly Bornstein, who quoted the Ridvaz, Rav Dovid ben Zimra, the rebbi of the Shitah Mekubetzes and the Arizal, who reframed the entire narrative as one of the most profound yesodos of the entire Yom Tov.

In cheilek gimmel of his teshuvos, the Ridvaz grapples with a question that anyone who thinks seriously about halacha must eventually ask. Why is chometz so different from every other issur in the Torah? Treife meat, cheilev, and yayin nesech are all subject to bittul. A drop of milk that falls into a pot of meat can be botul b’shishim. Sometimes you need a hundred times. But there is bittul. The halacha has mechanisms for dealing with small amounts of issur. That is how it works.

Except with chometz. Chometz on Pesach is never botul. Not one part in sixty, not one part in a million. The Ridvaz considered the conventional answers, dovor sheyeish lo matirim, and the like. But he is not satisfied. He takes another route, and here the Chida explains that “The remez is the pshat.”

The answer, says the Ridvaz, is rooted in what Chazal tell us in Maseches Brachos. The Gemara describes the yeitzer hara as se’or shebe’isa, the ferment in the dough. In the new sourdough culture, we all appreciate what that means. That starter, that tiny drop of culture, causes the entire dough to rise. It’s the starter, as they call it. It causes the dough to rise. Chometz is not merely a beautiful remez for the Shabbos Hagadol drosha. It is the yeitzer hara. And there is no room for even a drop of him.

Just as a single drop of sourdough culture introduced into fresh dough does not stay a drop—it spreads, it permeates, it transforms the entire mass—so too the yeitzer hara. Given any foothold at all, even the tiniest one, it works its way through everything. Chazal say, “Leitzanus achas docheh me’ah tochachos,” one cynical remark pushes away a hundred rebukes. It’s not botul one in a hundred. It’s not a drush. It’s a Gemara. This is the actual reason chometz cannot be botul, because you cannot be mevatel a yeitzer hara. You cannot say about your inner ferment, “It’s less than a kezayis. It doesn’t count.” It always counts.

I began to understand why there are massive asifos on issues for which many would think a simple letter and shmuess would suffice. The battle against what many perceive as a tiny drop of se’or, a small problem, an insignificant crack, is not merely that. Did physics care that the Space Shuttle Challenger had a hairline fracture in an O-ring seal? A fissure thinner than a sheet of paper caused an explosion that shook the world. The engineers who dismissed it, who essentially said, “It’s botul. The system is too large for something so small to matter,” were tragically, fatally wrong.

The yeitzer hara is the master of appearing small. And then…

We need biur chometz. And we need bedikas chometz. Active, deliberate, candle-in-hand investigation of every corner, every crevice, every place you’d rather not look. The most dangerous piece is not the loaf sitting on the counter. It’s the piece tucked away in a recess. The piece you forgot about, sitting quietly in the dark. You must shine a light on it. Shine before the rise. And if you don’t go looking, with the willingness to move heavy furniture, it will find you.

The response must be dramatic. Bittul alone is not enough, which is why we both say bittul and do biur. Because even after you have legally nullified it in your mind, the Torah says: Go find it anyway and burn it. The goal is not just halachic compliance. The goal is genuine inner freedom. Chag Hacheirus cannot coexist with a yeitzer hara that has been granted squatter’s rights in a quiet corner of the soul.

We all have our small chometz. The little grievance we’ve been carrying since Sukkos that we haven’t quite let go of. The habit we know is corrosive, but is, after all, so small. The pride that flares up occasionally, not often, just now and then, nothing serious. The cynicism about lomdei Torah, about the tzibbur, about our rov, or even gedolei Yisroel, that we’ve allowed to settle somewhere in the back of our minds like a crumb behind the stove. We don’t think about it much. It’s pachos m’kezayis. We think it’s botul.

But se’or shebe’isa doesn’t need much to work with. It needs one drop, left unaddressed, given a little warmth and a little time. And before long, the dough has risen, and you don’t quite recognize yourself anymore.

The bedikah is about looking honestly at what has been fermenting. What small resentment has been quietly rising? What minor compromise has been slowly expanding? What bit of gaavah has been working its way through the dough of the personality? The candle of bedikas chometz, say the Chassidishe seforim, is the neshomah—ner Hashem nishmas adam. Hashem gave us an inner light specifically so we could search the dark corners.

So yes, clean the kitchen. Check the pockets. Move the refrigerator if you must. The Ribbono Shel Olam loves a Yid who takes even the smallest crumb seriously.

But while you have that candle lit, point it inward, too. The most dangerous chometz is the kind that has been sitting so quietly for so long that you’ve stopped noticing it’s there. Get rid of it. Even the slightest morsel.

Just saying.