One of the major debates in Jewish thought relates to the appropriateness of ascribing reasons for the mitzvoth of the Torah. One approach asserts that if G-d commands, we must obey and do, period. No loyal soldier would dare question an order from his commander and to question the why's of G-d bespeaks, even if ever so slightly, a lack of trust in G-d.
Furthermore, our Sages were well aware of the danger of allowing reasons to shape the applicability of the mitzvah. Once we determine the reason for a mitzva, it is quite reasonable to argue that if the reason no longer applies neither should the mitzva. There is great logic to this view and, as surprising as this may be for many, this is the view of the Rabbi Shimon (Sanhedrin 21a). Even Rabbi Yehuda who normally disagrees, agrees that if the Torah itself gives a reason and that reason is no longer applicable the mitzva no longer applies[1]. That being said, without an explicit reason given in the Torah, it is rather presumptuous to assume that humans can fathom the depths of the Divine will.
The necessity to just perform the mitzvoth and not ask why is alluded to as the parsha opens. "G-d spoke to Moshe saying; Tzav, command, Aharon and his descendants saying, this is the Torah" (6:1-2). Quoting our Sages, Rashi teaches that the word tzav means "readiness to perform for now and for all generations". When one receives a command the only response must be to carry it out immediately. The closer one is to G-d the more important that obedience becomes. Thus kohanim zrizim hem, the kohanim are quick to obey the mitzvoth. Working in the Temple how could it be otherwise? And this eagerness to observe the mitzvoth allowed the Rabbis to declare that ein shevut bamikdash, that rabbinic enactments designed to safeguard the law are not necessary in the Temple. Safeguards are only needed when people are a little lazy.
Nonetheless, obeying does not preclude questioning and exploring the reasons for the mitzvoth. The overwhelming thrust of Jewish thought is that we are permitted, perhaps even obligated, to seek out reasons for the mitzvoth. True, there are risks involved – and many stopped doing mitzvot because they believed the reasons no longer applied – but the greater the risk the greater the reward. We are not meant to be robots in our observance of mitzvoth. Torah lo bashamayim hee, the Torah is not in heaven but rather meant for man. And the greater the understanding the greater the impact of the mitzvah.
It is not even important if our reasons are right. Having reasons that are meaningful to us can inspire us in our observance. While the solider may have no choice but to obey, man is granted free choice and most people have difficulty observing that which they do not understand. Many have walked away from mitzvah observance after unfortunately being told that we don't ask questions.
The concept of chukim, mitzvoth the rationality of which is difficult to comprehend i.e. the strange ritual of the red heifer, the maftir of this week, teach that man cannot plumb the depths of the Divine will and that ultimately all mitzvoth must be accepted as G-d's command. It is only the level of understanding or lack thereof that changes. Once we recognize that all reasons are speculative then seeking meaning becomes a crucial component of our beautiful desire to serve and understand G-d.
Lacking understanding of the rationale of the mitzvot will inevitably lead to performance of mitzvot by rote. This is far from ideal, though generally technically acceptable. Except, that is, in the area of korbanot.
Korbanot in of themselves are at best meaningless and at times a lot worse. Every ritual is a mechanism to lead us to ethical excellence. We eat matza to remind ourselves how to treat the stranger, sit in a Sukkah to feel what it means to be homeless, and fast on Yom Kippur to inspire us to support the hungry. And we bring korbanot to come closer to G-d and man. Over and over and over again, our prophets lament the mere offering of sacrifices. If bringing a korban does not positively impact upon us, they are but "vain offerings, incense of abomination they are to me" (Yishayahu 1:13).
That korbanot are external expressions of internal growth explains two unique halachot regarding korbanot. Only in the laws of korbanot can improper thoughts actually invalidate the korban, even at times render the eating of such meat punishable by karet, excision from the Jewish people. At the same time only by korbanot can mere recital of the words be considered equal to actually offering korbanot. One can "bring" a korban without actually offering a korban. Hence the placement of the sacrificial order in the daily prayer book, recital of which according to many fulfils a Biblical command.
May we merit that we not only observe the mitzvoth but find meaning and relevance in them helping us to come closer to G-d and man.
[1] This is basis of the ruling of the Shulchan Aruch (Yoreh Deah #270:2) that the mitzva to actually write a sefer Torah is no longer applicable and has been replaced with a mitzva to have a Jewish library. The Torah explicitly tells us the reason we write a sefer Torah is to learn and teach from it (Devarim 31:19). Ever since permission was given to put the Oral law to writing we learn using books – it even being considered disrespectful to take a sefer Torah out of the Aron Kodesh to learn from.
[2] Psukei Dzimrah is no more than an act of piety, not even rising to the level of minhag.