Two Methods One Purpose
“פנחס בן אלעזר בן אהרן הכהן השיב את חמתי מעל בני ישראל” (Pinchas, son of Elazar, son of Aaron the Kohen, removed My anger from the Children of Israel) . Rashi brings the rabbinic tradition , “Because the men of the tribes were ridiculing him, saying, ‘Have you seen this son of Puti (They called Pinchas“ben Puti” in reference to the fact that he was a maternal grandson of Yisro, who had been a priest in the service of idolatry), whose mother’s father stuffed calves in honor of idol-worship, and yet he had the audacity to eliminate a Jewish tribal prince? Therefore Scripture traces his patrilineal decent directly to Aaron.”
This appears a bit problematic. The tribes most definitely had prior knowledge that Pinchas was descended from Aaron. Yet in spite of this, they did not refrain from belittling him. If so, what does the verse accomplish by emphasizing this obvious point?
The Gemara  relates that although Aaron and Elazar were Kohanim (priests), Pinchas was not a kohen prior to his killing Zimri. He received priesthood as a reward for his action. This too places us in a dilemma. Killing is a deed that is coarse and the Kohen’s job is to bring the people close to G-d, which requires the utmost refinement . How is it possible that Pinchas received the reward of nobility to become a Kohen as a result of manslaughter?
When the Jews sinned by creating the golden calf Aaron was approached and instead of acting zealously he responded in a seemingly lax and indifferent manner. We know from the words of our Rabbis  that Aaron was the prototype of an “אוהב שלום ורודף שלום” (lover of peace and one who pursued peace at every opportunity). Thus his reaction to the demands of the Jewish people at that perilous time is within character.
Pinchas, his progeny, however acted in a manner that seems to be in direct conflict with the nature of his grandfather. Therefore the tribes ridiculed him. They saw his actions as being in direct opposition to the reaction befitting one of his distinct pedigree. So they reasoned that this character trait most definitely must stem from his maternal side. However, a deeper awareness into the nature of these exalted men may perhaps guide us to a different conclusion.
At the time that Aaron was persuaded to help create the golden calf, the Jewish people were a young nation just three months out of our bondage in Egypt. Therefore, it was understandable that Aaron, with the love he had for all Israel, took a non-confrontational approach . However, when Zimri sinned with the Midianite woman, it was already forty years after they had left Egypt, and the original generation had almost all perished in the desert. The Children of Israel were now a new generation, almost all of whom had never suffered at the hands of the Egyptians, and had been born and matured in the holy camp surrounding the Tabernacle. It is therefore understandable that Pinchas had to take a tougher position.
The verse in Koheles (Ecclesiastes)  states, “there is a time for everything… a time to remain quiet and a time to speak up.”
The Gemara relates  that the Evil Inclination has seven different names. In yet another passage the Gemara says  “Satan, the ‘Evil Inclination’ and the ‘Angel of Death’ are all one. He is just referred to by a variety of names.” What these two Gemaras are possibly trying to tell us is that the trials and tribulations caused by the Evil Inclination are constantly changing. The Evil Inclination is chameleon-like, constantly presenting himself as a different character, thereby ensnaring the unprepared individual.
We know the words of our Holy Rabbis , “A person’s evil inclination is constantly trying to overpower him and thinking of new ways to bring him down.” The Beis Halevi  explains these two traits as follows. The Yetzer Hara (evil inclination) seduces us daily, and when he sees that it he is not successful he persists with the same method but a bit harder. When this too is not successful, he changes his approach entirely, to the opposite extreme.
This teaches us that in order to combat our Evil Inclination we must be constantly engaged, lest we take things for granted. Then without our realizing, he (the Evil Inclination) has us totally at his command.
The tribes were mistaken in assuming Pinchas’ actions were divergent from Aaron’s conduct. At the time of the Golden Calf, Aaron remained silent. This does, by no means imply that had Aaron been alive for the incident of Zimri he would have acted any differently than Pinchas. What helped previously to contend with the Evil inclination, does not necessarily help at a later time.
Therefore, the verse emphasizes that Pinchas is a grandson of Aaron; implying that his act was not a deviation from his family tradition as the tribes had falsely assumed. Rather, it was a direct outcome of his ancestral heritage. Hence his reward was that he should become a Kohen like his grandfather, Aaron. This reward proves to us that Pinchas continued in his footsteps.
From the Torah’s correlating Pinchas to Aaron we learn a two-fold lesson. We must constantly find new techniques to ward off our inborn desire to do evil; but the methods must be fully rooted in the ways of our Holy Sages. If we are embedded in the old ways, we can vary our approaches in fighting off the Yetzer Hara (Evil Inclination) and his devious ways. As we see from Pinchas, the Torah recognizes his actions as consistent with the ways of Aaron even though they were seemingly different.
Rabbi Dovid Sochet
 Bamidbar – Numbers 25:10
 see Medrash Tanchuma 1, Sanhedrin 82B
 Tractate Zevachim 101B
 Indeed the Zohar 3:214A rules that a Kohen who has committed murder is forever prohibited from performing the service in the Temple. The Gemara in Brachos 32B seems to be in agreement. The Tosfos Yom Tov in Bechoros 7:7 also rules so.
 Avos 1:13
 See Artzos Hasholem (Rabbi Meir Leibush Malbim 1809-1879) Drasha (exegesis ) 2, where he explains the reason why Hashem waited forty years to bring the children of Israel to their land. The evil ways of the Egyptians was so engrained in Bnei Yisroel that it had become their second nature. By being in the desert forty years they became a nation that attained lofty spiritual levels. This is perhaps a stepping stone to the point I am trying to bring out in regard to Aaron. He recognized that Bnei Yisroel at that time had not yet shed themselves of the deviant ways of the Egyptians. He therefore took a less aggressive approach.
 Tractate Succah 52A
 Tractate Bava Basra 16A
 Tractate Kidushin 30B
 Rabbi Yosef Dov Soloveitchik (1820-1892), See Beis Halevi parshas Bo.