The Mishnah discusses the mitzvah of bedikas chametz and states, "החמץ את בודקין", meaning "we check the chametz." Rebbe Yehoshua of Belz zt'l asked, shouldn’t it be written as הבית את בודקין, "we check the house," because it’s the house we check, not the chametz?
Years later, his son, Rebbe Yissachar Dov of Belz zt'l said he could answer the question with a mashal:
Two business partners arrived at the market and successfully sold all their merchandise. They put their earnings into a money pouch and headed back to their hometown on foot. Halfway home, they stopped in a field to lie down. They needed a break. Their only concern was what to do with the money pouch. They looked around the area they were in and couldn’t spot anyone in the vicinity, other than some cows grazing in the pasture. They hung their moneybag on a branch and went to sleep under that tree.
But they forgot that where there are cows, there is a shepherd nearby. When they were fast asleep, the shepherd took their money. The shepherd contemplated his options. He couldn't run away because he had a job to do; he was hired to watch the cows. But if he remained nearby, the merchants would drag him to the police.
He decided to fill the money bag with cow manure, so the merchants would not realize that he had stolen the money. By the time they would grasp what had happened, he would be far away from the scene of the theft.
The merchants awoke and were happy to see their moneybag still hanging on the tree. They didn’t suspect a thing and continued on their journey home. When they opened their bag and saw that it was filled with manure, they wondered, "How did the cows manage to climb up the tree and put manure inside?" They resigned themselves to their loss because what could they do? You can't quite bring a cow to court, can you?
When Rebbe Yissaschar Dov told this story, the chassidim laughed, although they didn’t understand how this story answers the above question of why the Mishnah says החמץ את בודקין (we check the chametz) and not that we check the house.
Rebbe Yissachar Dov's son, Rebbe Aharon zt'l, was also present, and the chassidim noticed that he was trembling from fear. They asked him why, and he said that he understood his father's intention. He explained that the foolish merchants should have turned their question into an answer. Since a cow can’t put manure inside a pouch, it must be that a cow didn’t do it; rather, a person did. They should have returned to look for the thief and taken him to court. Perhaps they would have gotten their money back.
Now we can explain why the Mishnah states that we check the chametz. This can mean that we examine our misdeeds and ask ourselves, "Where did they come from?" These aren’t the type of deeds I wanted to do. I wanted to do mitzvos. How did I end up with so much evil on my hands?”
After contemplating this, people generally conclude that they are at fault, and it is their responsibility. But the real culprit is the yetzer hara. The yetzer hara tricked you, enticed you, and brought you where you are today. Recognize this, and don't lose hope. Identify the culprit and fight him.
