The Mishnah (Berachos 33b) rules that one who says, “As Your mercies, G-d, devolve on the mother bird and its nest, so too, have mercy on us,” must be silenced. The Gemara explains that the requirement of sending away the mother bird prior to taking her eggs is solely a Divine decree, not based on the desire to be merciful to the mother bird, as the forbidden prayer would seem to imply. Yet the Sages themselves say (Devarim Rabbah 6:1): “…So, too, G-d’s mercy extends to the birds, as it says, ‘When you discover a bird’s nest…send away the mother…’”
To resolve this contradiction, we must distinguish between a taste and a reason. If we were asked why we eat, we would answer that we must eat in order to live. If questioned further why we eat bread and not stones, we might refer to the necessary nutrients available in bread but not in stones. But if asked why human beings need these nutrients, or why we are capable to extracting needed minerals from bread and not rocks, we could say nothing more than that is how G-d created the world and the answer lies exclusively in His mind.
Even though we eat to stay alive, Hashem created the world in such a way that our food also has a pleasing taste and aroma. But that taste should never be confused with our reason for eating. Even if our taste buds were destroyed and we could not taste our food, we would still have to eat. And if we let our taste buds guide our choice of foods, we might soon die of malnutrition.
The mitzvos are the spiritual nourishment of our neshamah (souls). Why or how a particular mitzvah nourishes our soul we cannot know any more than why G-d created bodies which require certain nutrients. But Hashem wanted the mitzvos to be palatable to us, so he infused them with taste — ideas and lessons — that we can understand. We must never confuse, however, the lessons of the mitzvos, with their underlying reasons.
If one entreats G-d, Who has mercy on the birds, to similarly have mercy on us, that entreaty reflects his own determination that he understands the reason for the mitzvah from G-d’s perspective. That is a mistake. We can never know why G-d decreed a particular mitzvah. But to learn from the mitzvah a lesson of mercy, as an enhancement to our performance of the mitzvah, is perfectly acceptable. That is the intent of the Sages in the Midrash mentioned above.
All mitzvos are intrinsically chukim, unfathomable Divine decrees. With respect to some, even the “taste” is obscure, and they are categorized as chukim, and in some the “taste” is more easily discerned, and they are called mishpatim.
Parah adumah is called Chukas HaTorah, a law of the Torah, and not Chukas HaParah, the law of the red heifer, because it demonstrates in the clearest fashion that the entire Torah is based on a Divine understanding beyond our ability to fathom – it purifies the impure yet impures the pure. Only when we base our performance of mitzvos on submission to the decree of the Creator, will they be performed with perfection.
(Rabbi Zev Leff)