Our Gemara on Amud Beis discusses the status of Cohanim in relation to their service in the Beis Hamikdash.  Are they considered agents of God, or our agents whom we appoint to serve God in our stead?  This has numerous applications, including if a Cohen, whom you vowed to not have benefit from, can stil bring your sacrifices. If he works for you as your agent, then he is bringing you a benefit. If he is merely following God‘s command, then he is really not doing anything for you.

Rashi (Bamidbar 8:2) brings a medrash that Aharon was distressed that he was not given the opportunity to offer sacrifices at the inauguration of the Beis Hamikdash, as the Nesi’im did (as described in the prior chapter 7, hence the sequitur to the lighting of the Menorah.)  Hashem thus consoled Aharon by telling him that “You will have the special mitzvah to kindle and trim the Menorah lamps every morning and evening.”

The Ramban (ibid) asks:

Why is this specifically labeled as a consolation instead of consoling him with the burning of the incense every morning and evening, which is the specific function of the Cohen Godol? And what about the Mincha offering which is brought daily by Cohen Godol personally, and what about the Service on Yom Kippur which is only valid if done by him (Aharon and subsequent High Priests)? Moreover, all the seven days of inauguration included many offerings brought by the cohaim alone? 

And if you say that Aharon was disheartened because his offerings were obligatory and he had been commanded to bring them, and he was dispirited because he did not bring a voluntary offering for the dedication of the altar as they did, this does not answer the question well because the lighting of the lamps with which He consoled Aharon was also a duty which he had been commanded! 

An additional question raised by the Chasam Sofer (Op. Cit.) is that even if we were to accept this was a consolation to Aharon, what about the entire Levite Tribe?  Every other tribe was able to have their princes offer a sacrifice, and this was a collaborative holiday celebrated by each tribe on the day of their offering.  Furthermore, the Chasam Sofer brings a “bomb kashe” from the Shalah:  The Levites were only dedicated on Rosh Chodesh Iyyar (I am not sure of the source, but from the narrative of the verses in Bamidbar chapter 8, at the very least this dedication occurred after the inauguration which was day 13 of Nisan.)  If so, how could they have been given the wagons to carry out their sacred duty on the first of Nisan, they were not yet authorized and therefore forbidden as non-Cohens in the service?

The Chasam Sofer uses the idea of whether Cohanim are our agents or agents of God to resolve the Ramban’s difficulty.  During the inauguration and before the Levites were dedicated there was yet no ban on non-Levites and non-cohanim to do service.  Thus, at that time, the Levites acted as our agents and not agents of God.  (Otherwise, how can an agent have more ability than the grantor of agency? In other words, how could the Levites be our agents in service, if we ourselves are not allowed to perform the service?)  The prohibition of a stranger performing the service was only from Rosh Chodesh Iyyar and onward, when the Levites were dedicated and set aside.

Now we can understand Aharon’s problem. Aharon was already set aside and dedicated as a high priest by God. Thus, all his activities were not performing the agency of his tribe, rather he was God's agent.  He was jealous for his tribe and himself, because the other tribes had the ability to effectuate their own sacrifices, albeit through agency of the cohanim, but they were the agents of the Tribe, since strangers were not yet banned from service. However, any sacrifices Aharon brought were not agents of the Levite Tribe as he could only be God’s agent.  In this way, the lighting of the Menorah is different because, according to the Rambam, the Menorah service could also be performed by a non-cohen. Thus this service remained authentically as the agency of the people. Aharon was consoled as he could light the Menorah as agent of the Levite Tribe (perhaps also including all of Israel too.)

Upon reflection, there is an adage from our sages, נֵר לְאֶחָד נֵר לְמֵאָה a lamp for one is a lamp for one hundred (Shabbos 122a). Metaphorically, the same lamp could provide light for many people, and unlike other resources, it is not diluted when more people use it.  Perhaps that is the significance why the Menorah was one of the only services that was technically allowed by a non-cohen.  That is, the light of the Torah or the Shekinah is accessible to all.  If we are to say this, perhaps I can offer a different (albeit poetic) answer to these questions.  Aharon’s distress was not for himself, but rather that there was a hierarchy, where sometimes one tribe would have more access than another.  Aharon who was known to be a “lover of peace and one who chased after peace” (Avos 1:12) was disturbed at the potential divisions and castes within Judaism as it could lead to quarrel.  Thus he was consoled when Hashem told him that in terms of access to wisdom, Torah and the light of the Shekina, all Jews are equal.  The Cohanim were merely the agents of the Jews. Indeed Mishna Horiyos (3:8) tells us: מַמְזֵר תַּלְמִיד חָכָם קוֹדֵם לְכֹהֵן גָּדוֹל עַם הָאָרֶץ a mamzer who is a Torah scholar precedes a High Priest who is an ignoramus, as Torah wisdom surpasses all else.