“ויקח קרח” – “And Korach took.” What did he take? The Gemara in Sanhedrin 109b says that it means that he took a מקח רע, a bad purchase, for himself. The Arizal says that Korach took from Kayin the צד הרע, the evil side. It says in Esther Rabbah that Kayin was the ראש להורגים, the head of the killers. Why do we call a killer “שפיכת דמים”, one who spills blood? While it is true that if all of one’s blood spills out of his body he will die, there are other ways to die. For example, if one is strangled, he will die without any blood coming out of him. It says in the sefer עץ חיים that a reviis of blood in a person is the ממוצע, the intermediary, between the guf and the nefesh, the body and the soul. The killer makes a separation between the guf and the nefesh. He kills the person; he is doing the opposite of what the blood does. Thus, the term spilling blood is used for killing, for by killing a person, it causes the blood to be spilled, to no longer be the intermediary between the guf and the nefesh.
The name “קין” comes from a lashon of “קנין,” meaning that he thought he was the only acquisition in this world; he was all that was needed. He was the antithesis of achdus, of being inclusive. His middah was one of being a רוצח, a killer, to not have achdus, to not have the guf and nefesh connected. The opposite of this middah was Aharon Hakohen. He did not look at himself as a קנין, but rather, he looked at himself as one who was always lacking. Aharon always sought to connect things together, to bring shalom between the guf and the nefesh, between man and his wife, between man and his friend. Aharon sought to connect to everyone and to connect everyone to Torah. Korach was the head of the רוצחים, creating separation between Above and Below, and conversely, Aharon Hakohen was connecting Above to Below. (שם משמואל)
Korach saw himself as a קנין and only saw himself, his own supposed greatness, while Aharon was exceedingly humble and only saw his lowliness. Moshe Rabbeinu told Aharon that it was specifically for that reason, that he saw himself as low and exceedingly humble, that he was the one chosen to be kohen gadol. This was the bad purchase that Korach took, the middah of Kayin, of only seeing himself.
This also explains the words of the Zohar Hakodosh that Korach came to argue on Shabbos Kodesh. By Shabbos Kodesh it says, “ויכולו”, which can be explained as to gather, in that Shabbos Kodesh came to gather the heavens and the Earth together, to make them one. That is why Shabbos is called “רזא דאחד”, the secret of the one. It is a time when the worlds are like one, and it is also to bring oneness amongst Klal Yisroel. Klal Yisroel become one with another and with the Ribbono Shel Olam. Korach came and was the antithesis of this middah of oneness. Rather, he came with the middah of Kayin, the exact opposite of oneness. He was all about himself, and he came to argue with the very essence of what Shabbos Kodesh is all about – achdus.
