When one reads the account of the rebellion of Korach he is struck by his seemingly foolish attempt to challenge Moshe Rabbeinu. Yet it is clear that at the time Korach succeeded in persuading huge numbers of people about the validity of his arguments against Moshe and Aron. Although the rebellion began with a relatively small number of people, by its climax, the Torah tells us that he gathered together “all of the assembly” against Moshe and Aron. How was he able to initiate such a powerful uprising against the men who had guided the Jewish people through countless miracles in the desert?
In order to answer this question, it is instructive to examine another problem in the parsha. One of the main arguments of Korach and his assembly was his opposition to the appointment of Aron to the position of Kohen Gadol. They argued that Moshe had personally made this appointment as an act of favoritism towards his brother. After the rebels were punished through various terrible yissurim, Hashem ordered Moshe to prove that Aron had been divinely appointed to his position through the test of the staffs whereby Aron’s staff miraculously blossomed proving conclusively that he deserved to be Kohen Gadol. After this test, all the discontent disintegrated
Rav Leib Chasman zt”l asks, why did Hashem order the test of the staffs only AFTER the awesome punishments that He meted out. Had the miracle of the staff blossoming taken place right at the beginning, it could have convinced the people of the invalidity of the arguments against Moshe and Aron, thus rendering the punishments unnecessary. He answers by teaching an important yesod in human nature. Korach knew that he could not defeat Moshe in a battle of logic, he knew that Moshe’s case was far too strong, and that Moshe was far too wise for Korach to rationally defeat him. Thus he resorted to the devastating weapon of leitzanus (mockery) through which he could belittle Moshe and Aron without having to logically justify his arguments. We see this in the words of Rashi when he explains how Korach was able to persuade so many people to side with him; The Torah says that he gathered the people against Moshe and Aron. The obvious question is how was he able to achieve such a monumental task; Rashi explains that he as able to do so through, “divrei leitzanus.”
Rav Chasman continues that leitzanus ignores the power of sechel and arouses the animalistic part of man where logic is meaningless. This explains the concept in the passuk in Mishlei that exhorts us not to rebuke the leitz; the leitz is not interested in any form of logical argument, rather he wants to continue with his own lifestyle and will belittle any attempts to change him. Another passuk in Mishlei tells us that the only way to humble the leitz is through yissurim; “Prepare punishments for the leitz.” The Mesillas Yesharim explains that ideally a person is supposed to grow and learn from his mistakes through Talmud Torah and chesbon hanefesh (self-contemplation), however the leitz is immune to such methods and therefore the only thing that can effect him is yissurim.
This, writes Rav Chasman, explains why Hashem only sent the miracle of the staffs after the punishments that struck Korach and his main supporters. The power of leitzanus to ignore logic is so great that it can even dismiss open miracles if they conflict with the leitz’s self-interest. Had the miracle taken place before anyone had been punished, the rebels would have found a way to dismiss it and ignore its ramifications through a mocking comment. It was only after the devastating punishments that the power of leitzanus was broken and the survivors could internalize the lesson of the blossoming staff.
This explains how Korach was able to persuade so many people to follow such a foolish course of action and challenge Moshe Rabbeinu. By nullifying their sechel through divrei leitzanus they became blinded to the dangers of following Korach.
The Mesillas Yesharim writes very strongly about the damaging nature of leitzanus. He argues that it is one of the main factors that prevents a person from developing the trait of zehirus (alertness against sin). Leitzanus prevents him from seriously analyzing himself by belittling that which is important and turning everything into a joke. He will not follow the rebuke of anyone, rather he will use mockery as a tool to escape serious self contemplation. Indeed it seems that leitzanus stems from a desire to escape the serious issues that a person must face if they want to serve Hashem in the best way. It is far easier to laugh off any possibility of growth rather than to face the challenge of dealing with one’s problems.
Korach used leitzanus to trick others but the yetser hara also utilizes it in order to make us trick ourselves into avoiding growth. We learn from Rav Chasman that the only way that the power of leitzanus can be weakened is through punishments. Rather than having to suffer unnecessarily, it is surely far more advisable for a person to go through the far lesser ‘pain’ of mussar. This can be done in a number of ways; learning mussar sefarim such as Mesillas Yesharim who discuss leitzanus in great detail; accepting rebuke from one’s Rabbanim and friends; or by making a simple cheshbon hanefesh and honestly examining himself. Surely such strategies are more desirable than the alternative of going through real suffering. a person opens himself up to genuine
 Korach, 16:19.
 Ohr Yahel, 3rd Chelek, quoted in Lekach Tov, Bamidbar, p.186.
 Rashi, 16:19.
 Mishlei, Ch.19.
 Mesillas Yesharim, Ch5.
 The root of the word ‘mussar’ is the same as that for yissurim (punishment), because real self-analysis and growth is painful and causes a certain degree of suffering.