Shmini talks about which animals and fish are kosher. It mentions one bird – the Chasida – which does chessed for its own species. Rambam says that the reason why certain birds are tomay is because their nature is evil and their midot is harmful. It is possible, therefore, that if people eat it, the nature will attach to the neshama of the eater. Here is the problem: The Chasida is not kosher but its nature seems to be good. So the simple answer is that this bird may just do chessed for its own species and not for others.
Doing chesed is one aspect of one’s nature. It could also steall, and be bad otherwise. It could just have that one trait. Another thing is that man has eaten non-kosher since the beginning of time and it doesn’t really seem to affect the soul. In fact, Rambam was a doctor – so how did he come to this? The Yerushalmi and Tosphos(? ) rule that a young baby is allowd to get nursed by another women – jewish or non-Jewish woman. The yerushalmi says (not sure here? ) that a young baby can even have the milk of a non-kosher animal.
It would seem that if the Rambam were correct we wouldn’t allow this. Why shouldn’t we worry about corrupting the nefesh of a child? So Rabbi Chesir’s answer is this: There are things that disgust us. Things that you can’t even look at, talk about, and make you nauseas. When something violates one of your sensitivities, human nature is to stay away from it. It is just as obvious in the other extreme. If a mother loses her son in a war, she might hold and smell his shirt forever.
If the torah tells us to stay away from a particular animal, or deed even, then we shouldn’t find loopholes to do it. Meaning Bacon bits shouldn’t be on the top of the grocery list. Otherwise it just demonstrates that we are not repulsed by something that is forbidden. These are evil birds – if you are not going to be repulsed, that develops a sense of tolerance for this species. Lack of sensitivity becomes an attachment to that item. Meaning that its not the molecules or enzymes in the animal that will make you evil.
Its that if you are aware that they are forbidden because they are evil, and you digest it anyway – you are in essence becoming attached to that evil. That is why a child can have that non-kosher milk. He’s not demonstrating an intentional attachment and tolerance for the evil. Hopefully, by acknowledging and then limiting ourselves from attachments that can have negative effects we can instead look for the attachments that will bring us closer to Hashem.