There is an interesting point R’ Baruch Rosenberg, R”Y of Slabodka, makes in his sichos (Divrei Baruch) that I want to take in a completely different direction than he does. He puts together two Midrashim that he puts together:
1) The Midrash tells us that the reason behind parah adumah was revealed only to Moshe. Shlomo tried to understand its secret, but even he was stymied.
2) There is another Midrash that lists four things that the yetzer ha’ra uses as ammunition to challenge us. One of the four is the law of parah adumah. How can it be, asks the yetzer, that the ashes of the parah are metaheir, but those who come in contact with the parah becomes tamei? How do you explain the self-contradiction?
It seems from the second Midrash that if not for the yetzer ha’ra, parshas parah would not present a challenge. Yet the first Midrash tells us that the law of parah adumah is incomprehensible -– it begs an inescapable and unanswerable question.
R’ Rosenberg concludes that although on the level of sod parshas parah will always remain incomprehensible, it is Torah to be learned and therefore must have some meaning for us. The yetzer ha’ra tells us it is void of sense altogether, but that is not true.
Had R’ Rosenberg read Keats or been married to someone who read Keats : ) I think he perhaps might have offered a different answer.
Keats wrote in one of his letters, “Several things dovetailed in my mind, & at once it struck me, what quality went to form a Man of Achievement especially in Literature & which Shakespeare possessed so enormously — I mean Negative Capability, that is, when a man is capable of being in uncertainties, mysteries, doubts, without any irritable reaching after fact and reason - Coleridge, for instance, would let go by a fine isolated verisimilitude caught from the Penetralium of mystery, from being incapable of remaining content with half-knowledge. This pursued through volumes would perhaps take us no further than this, that with a great poet the sense of Beauty overcomes every other consideration, or rather obliterates all consideration.”
It’s Coleridge and the Enlightenment thinkers who are, for Keats, the yetzer ha’ra the Midrash speaks of. The obsession with arriving at philosophical answers, scientific answers, arriving at THE truth that resolves all doubts and questions, is something that Keats, a Romantic poet, rejected. Kears preferred savoring the beauty of the mystery itself, the beauty of multiple contradictory perspectives that the poet can slip in and out of.
It’s not the fact that we can understand the parsha of parah on at least some level that protects us from the challenges yetzer. It's our acceptance of unfathomable mysteries and paradoxes which is the ultimate shield.