"And it was on the eighth day, Moshe called to Aharon and to his sons and to the elders of Israel." (Vayikra ix, 1) "It is the eighth day of the milu'im [consecration], as well as Rosh Chodesh Nissan, the day on which the Mishkan was established." (Rashi, op cit)
Rabbi Avraham Yitzchak Kook, as part of his proverbs relating to the months (Megged Yerachim), writes the following about the month of Nissan: "The Mishkan of G-d and everlasting freedom / Together will make a spring 
One must know how to channel the strengths into true and holy actions.
nation." Spring expresses the renewal of natural existence - trees blossom and flowers grow in their wealth of colors. A person connected to the world surrounding him feels refreshing and new forces flowing through him, and the entire people can also reach new spiritual heights in this period. Yet, this renewal also includes dangers, as one must know how to channel the strengths into true and holy actions, and not just into subjective, minor deeds.
Nadav and Avihu possessed tremendous strengths, as Rashi explains on the pasuk, "And Moshe said to Aharon: This is what HaShem spoke, saying, 'With those near Me I will be sanctified, and in front of all the people I will be honored'...." (x, 3) - "Moshe said to Aharon: Aharon my brother! I knew that this House would be sanctified through those close to HaShem and I thought it would be either through me or you, now I see that they are greater than both you and I."
This power led to a tremendous enthusiasm in the service of HaShem, and therefore "each man took his censer and put fire in them and placed incense on it and they offered before HaShem strange fire which He had not commanded them" (x, 1); yet, since HaKadosh Baruch Hu had not commanded it, this fire was a strange, forbidden fire.
Aharon's reaction is, "And Aharon was silent" - silence and an acceptance of judgment out of a deep recognition of the Divine truth that is revealed in our world through might and judgment, as well as through kindness and mercy. This response teaches us an important principle in the service of HaShem, both inside and outside of the Mikdash - that we have no "demands" of HaKadosh Baruch Hu, but only requests that HaShem in His great goodness will do good to us, through which His Name will be sanctified in the world and his Shechinah will be revealed. Only in this manner do we become pure vessels, capable of receiving the Shechinah, so that it should rest amongst us.
Rashi (ix, 23) explains: "All seven days of consecration, during which Moshe erected the Mishkan, served in it and dismantled it every day, the Shechinah did not rest in it, and Israel were ashamed and said to Moshe, 'Moshe Rabbenu, all these efforts we made so that the Shechinah should rest amongst us and we would know that the sin of the calf has been atoned for.' Therefore he said to them: 'This is the thing that HaShem commanded that you should do, so that the glory of HaShem may appear to you' - my brother Aharon is more worthy and important than me; through his sacrifices and service the Shechinah will rest on you, and you will know that HaShem has chosen him."
The Shem MiShemuel raised a difficulty regarding this:
"How could Aharon be more worthy and important than Moshe? Scripture testifies (Devarim xxxiv) 'And no prophet rose again in Israel like Moshe,' and it also states (Bamidbar xii): 'And the man Moshe was more humble than any person on the face of the earth', and hence Moshe was more humble than him. A further difficulty arises from the Gemara in Chullin (89a), which states: 'That which is stated in connection with Moshe and Aharon is greater than that which is stated in connection with Avraham. For in the case of Avraham it is written, 'And I am dust and ashes'; whereas, in the case of Moshe and Aharon it states, 'And what are we?' (meaning that they had no existence at all) Moshe and Aharon are equated here, in that neither of them had any existence in their own eyes; in that case, the words of the verse 'And the man Moshe was more humble than any person on the face of the earth' remain to be understood."
In order to resolve these difficulties the Shem MiShemuel teaches us that there are two types of humility. There is the kind in which the person knows and feels his own lowliness, and there is the kind of humility in which even though the person is aware of his status, nevertheless, in comparison with his knowledge and grasping of the greatness of G-d, he is considered in his own eyes a compete nullity. An example of the second type is Rabbi Yosef, who responded to the statement of the Mishna in Sotah that "after Rebbi [Yehudah HaNassi] died, humility and fear of sin were revoked": "Said Rabbi Yosef to the Tanna: 'Do not add "humility", for there is me (do not include humility in the Mishna, for I am humble)'." (Sotah 49b) Even though he knew his standing and that he was humble, Rabbi Yosef nonetheless did not consider this as granting him any sort of existence.
The difference between Moshe and Aharon lies in these two understandings of humility. Moshe was aware of his standing, for he merited something no other person merited, and he himself transcribed his greatness in the Torah: "And the man Moshe was very humble", "Not so with my servant Moshe; amongst all My house he is faithful", "And no prophet rose again in Israel like Moshe". Nonetheless, with all he achieved in the knowledge of G-d, more than any other person, he knew that his personal existence is not more important than that of any other person, and he considered himself a complete nullity. Aharon, on the other hand, saw his own lowliness and was utterly lowly in his own eyes, certainly after the sin of the calf that was fixed in his thoughts, in the manner that the Psalms state, "And my sin is always before me" (Tehillim 51); and as the Ramban says, the altar appeared to Aharon as a calf.
Thus, on the one hand Moshe and Aharon were both equal in humility, as they said, "And what are we?" Yet, on the other hand, there remains a difference between them. These are all the words of the Shem MiShemuel.
We learn in theTanchuma (Shemini 3): "The reason why it states 'And it was on the eighth day' is because all 
Even though he recognized his nothingness in the face of G-d, he nonetheless stood up for himself.
seven days that Moshe was at the burning bush, HaKadosh Baruch Hu said to him, 'Go on My mission,' and he replied to Him, 'Send the one You usually send.' HaKadosh Baruch Hu said to him: 'I am telling you go! And you tell me "Send the one You usually send"? Upon your life! Later I will punish you. When the Mishkan is built you will think to yourself that you will serve as the Kohen Gadol, and I will tell you to call Aharon to serve.' It therefore states, 'And it was on the eighth day, Moshe called to Aharon and to his sons.'"
From this Midrash we can learn about the nature of Moshe's humility, that even though he recognized his nothingness in the face of G-d, he nonetheless stood up for himself and recognized his greatness. This attribute is suited to the nation's leader - he must act out of strength and confidence joined to humility. We find this trait in Moshe at the sin of the golden calf as well, when HaKadosh Baruch Hu announces to him, "Go descend, for your people that you brought out of Egypt are corrupted" (Shemot xxxii, 7); immediately followed by, "And Moshe entreated before HaShem his G-d..." and afterwards, "And now, if You will forgive their sin - and if not, please wipe me out from Your book that You have written." This shows tremendous strength, suited to the nation's leader.
Unfortunately, nowadays there are powerful and determined leaders, but they do not possess the central and most important foundation in the leadership of the people - humility. They therefore commit serious errors in the leadership of the people.
Aharon is deliberately chosen to be the Kohen Gadol, with his unique trait of humility enabling him to be a whole vessel in the Mikdash service, as with Aharon's silence. On the pasuk, "And Moshe and Aharon came to the Ohel Mo'ed [Tent of Meeting], and they exited and blessed the people...." (ix, 23) Rashi explains: "Once Aharon saw that all the sacrifices had been offered and all the actions performed, and yet the Shechinah had not descended to Israel, he was upset and said, 'I know that HaKadosh Baruch Hu is angry with me, and it is on my account that the Shechinah has not descended to Israel (presumably due to the sin of the calf).' He said to Moshe: 'Moshe my brother! Is this what you have done to me - that I have entered and been shamed? Immediately, Moshe entered with him and they prayed for mercy, and the Shechinah descended upon Israel."
Here, too, we find Aharon's unique brand of humility, for he was convinced that it was his fault that the Shechinah was not resting upon them. Yet, the Midrash (Vayikra 9:3) teaches us:
"When Israel made the calf, they first approached Hur [and] said to him, 'Arise and make us gods.' Since he did not listen to them, they rose against him and killed him. After that, they approached Aharon [and] said to him, 'Arise and make us gods.' When Aharon heard this, he was immediately fearful, as it says, 'And Aharon saw and he built an altar before him' - he was fearful because of the slaughter [that had been performed] before him. Aharon said: 'What should I do? They have killed Hur, a prophet. If they proceed to kill me, a priest, the words of Scripture will apply to them - 'Will a priest and prophet be killed in the Mikdash of HaShem?' (Eichah ii) and they will immediately be exiled.'"
We learn from this that Aharon's role in the sin of the golden calf sprung from his great love of Israel. As this is a great mesirut nefesh [act of devotion] of Aharon's, why then did he think that the Shechinah did not rest because of him? This is Aharon's unique trait of humility, on account of which he merited to be the Kohen Gadol.
The interesting part is that Moshe needed to enter the Mishkan with Aharon in order to pray. Why couldn't Aharon pray for himself? According to our explanation, the matter is clear: Moshe's brand of humility is suited for prayer, whereas Aharon's is not. If so, it becomes clear that in order for the Shechinah to rest, Moshe and Aharon must be joined together, for only their combination in complete harmony causes "fire came out from before HaShem and consumed upon the altar the burnt offering and the fat...."(ix, 24)
When we understand that HaKadosh Baruch Hu brought us out into everlasting freedom and therefore we serve HaShem, and all our strength is from HaKadosh Baruch Hu, and connect this to the Shechinah's revelation through an understanding of the process of that time, then it becomes "the spring of nation," in the words of Rabbi Kook's proverb. Only in this manner will we succeed in finding new and fresh strengths and not fall into the pitfall of
Divine Providence is complicated and profound, and we must attempt to understand and connect to it in great humility. pride.
As is well known, the culmination of the building of the Mishkan occurred on the 25th of Kislev, yet its final erection happened on Rosh Chodesh Nissan. Even when we had already arrived at the eighth day and expected the Shechinah's revelation, the Shechinah still did not descend, and the delay we spoke of occurred, as well as the crisis involving Nadav and Avihu. The feeling of the nation as a whole, and of Aharon in particular, should have been one of total despair, for according to "our plan" the Shechinah should have descended a long time ago, and things have not worked out as we thought. This clarifies for us an important principle - Divine Providence is complicated and profound, and we must attempt to understand and connect to it in great humility; only in such a manner will we succeed in acting with G-d.
If we understand and internalize these matters in the complicated reality of today, then we will not offer extreme and mistaken reactions, but rather we will merit making the Name of Heaven beloved through our hands, following the path of Moshe and Aharon.