Parashat Chukat begins with one of the strangest of all the commandments in the Torah. Moses instructs the Israelites to slaughter and burn a cow that is entirely red and to save the ashes for a ritual to purify people who have come in contact with a dead body. If that's not odd enough, the passage also contains this paradox: the person who gathers the ashes of the Red Cow is rendered ritually unclean by the same ashes that are used to purify others (Number 19:9-10).
The paradox has been apparent since ancient times. In the midrash, wise King Solomon is said to have exclaimed, "I succeeded in understanding the whole Torah, but, as soon as I reach this chapter about the Red Cow, I searched, probed and questioned. 'I said I will get wisdom, but it was far from me.'" (Yalkut Shimoni 759; Ecclesiastes 7:23).
Ever since, there has been an argument in Judaism about how inexplicable laws in the Torah should be viewed. Some say that God's laws are beyond question and must be observed without question or explanation. According to this point of view, the mitzvot are their own justification—we fulfill them because God has asked us to do so. The more inscrutable a law is, the better it is to teach us this lesson.
This is the logic of the Vilna Gaon (Rabbeinu Eliyahu of Vilna), who taught that any attempt to explain a law would lead to the violation of the law. He says that once people begin coming up with reasons for observing a law, they begin looking for cases in which the reason does not apply and excuse themselves from observing the law in those cases.
For example, if I believe that the reason for the prohibition on playing musical instruments on Shabbat is to prevent me from repairing an instrument that breaks on Shabbat, I might think that it is okay to play the instrument as long as I don't repair it. The rational explanation, argues the Vilna Gaon, actually leads to the law's violation. He says that it's better not to explain the laws and just to observe them without question.
If that seems like shaky reasoning to you, you are not alone. The Rambam (Rabbi Moses Maimonides) ridicules the Vilna Gaon's objection (five hundred years before the Vilna Gaon was born!). According to the Rambam, those who believe that it is impermissible to consider rational explanations for the commandments suffer from "a certain disease of the soul." He explains:
Those people imagine that if the laws appear to make any sense at all or to serve any purpose, others will assume that the laws must have come from human reason and not from God. It is only if the laws have no reason and serve no purpose that people will attribute them to God, since no human being could come up with something so inexplicable. According to this weak-minded theory, human beings are more perfect than our Creator! For we do things that have a purpose, while God's actions are different; God commands us to do what is of no use to us, and forbids us to do what is harmless. Far be it from so! On the contrary, the sole object of the Torah is to benefit us. (A Guide for the Perplexed, Section 3, Chapter 31)
So, then, how would the Rambam explain the law of the Red Cow whose ashes render the impure pure and the pure impure? The Rambam says that the laws of ritual purity serve to create awe and reverence for God and the Temple in the hearts of the Jewish people. He seems to suggest that the ashes behave the way they do simply because there needs to be a way to purify the ritually impure and it needs to be something miraculous. Red Cow ashes are as good at fulfilling those requirements as anything else might be.
Still not satisfied? Here's my take on inscrutable laws: the explanation is that there is no explanation.
In the time of giving of the Torah, laws like that of the Red Cow made sense to people based on their traditions, customs and understanding of the world. There is no reason to assume that the Torah's first audience was more mystified by the ritual of the Red Cow than we are mystified by the pageantry of halftime at the Superbowl. On reflection, the ancient Israelites surely saw the strangeness of the law, but they accepted it as "the way we've always done it." Even if they did ask, "What is the point of this?" the answer could only have been the same one we give about the Superbowl: "That's just the way it is."
The common cultural understandings for these laws disappeared millennia ago (long before the time of the rabbis of the Talmud and midrash), and we are left only with the mystery. But that's a good thing. Mystery is much more interesting than a cultural oddity. Our reflection on the Red Cow reminds us that there is so much about the world that we do not and cannot understand. We find that we don't really understand the past. We certainly don't understand the future. And, perhaps, we will learn at last that we don't really understand the present, either.
The purpose of the Red Cow is to remind us that we submit ourselves to a universe and a God that is beyond our ken. We don't observe commandments just because we understand them, we observe them also because we wish to celebrate a world that we don't understand.