Musar su Levitico 19:19

שדך לא תזרע כלאים...בהמתך לא תרביע כלאים . The reason for this string of forbidden mixtures (19,19) is that the Creator in His wisdom saw fit to separate certain species; the account of their creation repeatedly underlines that they were created למינהו, each according to its kind, even the lowly grass (Genesis 1,12 et al). It is incumbent upon us not to upset G–d's order in the universe. We have explained that every blade of grass has a Mazal which supervises and encourages its development.

Let us now explain our Parshah. There were three distinct groups of people involved in the quarrel. The central contender was Korach. He was the scoffer about whom the Psalmist had said that one should not sit in the company of scoffers, as we have explained earlier. Datan and Aviram were wicked people, as we know from Moses saying in Numbers 16,25/26: "Moses went to Datan and Aviram followed by the elders of Israel. He said to the congregation: "Please depart from around the tents of these wicked people, etc." Concerning Datan and Aviram, the Psalmist had said in the same verse: "Hail to whoever has not followed the counsel of the wicked people." The third group were the two hundred and fifty men who sinned against their souls, as we know from 17,3: "and take the censers of these people who have sinned against their souls, etc." Concerning those people our Psalm said "hail to whoever did not stand on the path of the sinful ones." The scoffer Korach, used matters connected with the soil as his subjects. Later, he made fun of Torah legislation involving sheep, etc., as mentioned in the Midrash quoted earlier. In all this he paralleled the behaviour of Cain, who had first brought a gift of פרי האדמה, the fruit of the earth. Abel, on the other hand, had brought an offering from the firstborn of his sheep. Cain had brought flax, Abel had brought wool. We know that there was a great deal of difference between the offering of Cain and the offering of Abel; G–d refused to accept the offering of Cain. This is why a mixture of wool and flax (linen), is considered כלאים, and is forbidden to be worn together in Jewish law (Leviticus 19,19). I have elaborated on this elsewhere.