In "We Plan, God Laughs," Rabbi Sherre Hirsch writes, "That massive cleaning effort is a metaphor. When your physical surroundings are cluttered, your emotional and spiritual self is cluttered. If your space is clean, then your mind is open and you can let God in."
(7) Throughout the seven days unleavened bread shall be eaten; no leavened bread shall be found with you, and no leaven shall be found in all your territory. (8) And you shall explain to your child on that day, ‘It is because of what the LORD did for me when I went free from Egypt.’
ספר נתיבות שלום ב:רמח
...ועל כן חמץ אסורו במשהו , כי הוא על דרך רקבון הפושה רחמנא לצלן בגופו של אדם , שאין נפקא מינה בגדלו של הרקבון , מכיון שהולך ומתפשט ומרקיב את כלו כמו כן החמץ שהוא שרש הרע הפורה ראש ולענה אין לו שעור ואסור אפלו משהו .
Sefer Netivot Shalom (Rabbi Sholom Noach Berezovsky, 20th C) vol. 2, p. 248
And therefore, chametz is forbidden in any amount, because it is like the rotting that spreads, God help us, in the soul of a person - there is no real difference in the amount of rot, since it continues to spread and rot continuously, since the chametz is the root of evil, that sprouts poison weed and wormwood, and therefore there is no minimum, it is forbidden in any amount.
(13th Century)
It's written ״You shall not make molten gods for yourselves” (Exodus 34:17) and afterwards it is written ״You shall keep the feast of unleavened bread (Exodus 34:18).” What does this [verse] have to do with that one? Rather, this is the explanation: one who eats chametz on Pesach is similar to one who worships idols.
מ"מ הרי אתה רואה שלא החמירה תורה בעכו"ם כמו בחמץ הילכך עדיין צריך טעם ועל כן אני סומך על מה שאמרו רז"ל במדרשות כי חמץ בפסח רמז ליצה"ר והוא שאור שבעיסה ולכן כלה גרש יגרש אותו האדם מעליו ויחפש עליו בכל מחבואות מחשבותיו ואפילו כל שהוא לא בטיל.
(16th Century)
In any case, you see here that the Torah was not as stringent with idolatry like it is with Chametz. Therefore, we still need a reason, and I rely on our rabbis, of blessed memory, in the Midrash that says that Chametz is an allusion to the evil inclination, and that is [also like] yeast in the dough [that will make it rise with even a little bit], and thus a person should banish it from himself, and search for it in all of the hidden areas of his thoughts, and even a slight trace is not nullified.
ר' אלכסנדרי בתר דמצלי אמר הכי רבון העולמים גלוי וידוע לפניך שרצוננו לעשות רצונך ומי מעכב שאור שבעיסה ושעבוד מלכיות יהי רצון מלפניך שתצילנו מידם ונשוב לעשות חוקי רצונך בלבב שלם.
R. Alexandri would say after prayers: Master of the universe! It is well known to you that we want to fulfill your will, but what interferes? The yeast in the dough and our foreign subjugation. May it be your will that you save us from their grasp and we will repent and fulfill your commandments wholeheartedly.
שאור שבעיסה – יצר הרע שבלבבנו המחמיצנו:
The yeast in the dough ... the yetzer hara (evil inclination) in our hearts that delays us/prevents us (chametz)
Rabbi Jill Hammer
In other words, our selfish impulses are kneaded all through us like yeast in dough, and it’s hard to separate them out. So Passover became a time to remove internal chametz as well as external chametz. The Chasidic thinker known as the Sefat Emet understands chametz as arrogance and matzah as humility, and points out that le-hachmitz means to miss an opportunity. To remove the chametz, the arrogance, is to discover more opportunities to connect and grow.
Rabbi Dayna Ruttenberg (www.danyaruttenberg.net, March 15, 2013)
These preparations for Passover can feel deeply spiritual in one way, but also invite us to ask whether we’re removing the spiritual chametz from our lives along with the physical stuff. A lot of traditional commentators describe chametz as fluffy, swollen (think of bread rising), and talk about spiritual chametz as the puffy, overextended parts of our ego; the way we try to posture and preen, to achieve renown rather than just existing as we are, being gentle and modest; a mere humble matzah, if you will.
It’s a lot harder to sweep out our illusions about ourselves, the ways in which we try to put ourselves first, the ways in which we hear others a little less well because we think of ourselves as more important, the ways in which we take shortcuts on our integrity and deepest values. There’s no cabinet in which we can lock away our pettinesses and our meannesses for a week.
Rabbi Danya Ruttenberg (continued)
Rather, we have to seek them out. Like the search for physical chametz that happens in the dark, with a candle, we need to be intentional in our attempts to collect all of the parts of who we’ve been that are not nourishing, that are dragging us down. We need to look for it, and we need to be willing to find it; to confront it, to face it, to name it, to take it from where it’s been hidden all this time. This work requires tremendous bravery.
And then, when we find it, we must burn it to give it up completely, to let it go, to transform ourselves by putting the worst of who we have been on the pyre.
We know, on some level, that like the cookie crumbs under the sofa, that some of it might come creeping back after Pesach is over. But it is the act of seeking it, naming it, and releasing it, to committing, year after year after year, to purifying the self and becoming the holiest version of who we are meant to be; it is the work of seeking out and releasing our internal leaven that is, in itself, an offering to God.