“Hashem said to Moshe, tell the Kohanim the sons of Aaron … the shall not become impure to any person in the nation”.
With the exception of his immediate relatives, a Kohen may never come into contact with a dead body. One wonders why this is. A clue is left for us in the Midrash. The Midrash cites R. Levi who tell us that it was in the merit of Aarons sincere fear of Hashem that he was given this Mitzvah, and he cites the verse, “Pure fear of God lasts forever”. It is challenging at first glance to grasp the connection between sincere fear of God and avoiding contact with dead bodies.
A person should always seek to wage a successful battle against his negative impulses, with his positive impulses. If this is successful, great!, teaches the Gemara. If not, it continues, he should study Torah. And if that does not help to get him to avoid doing the wrong thing, then let him recite the Shema. And if even that does not work, then he should think about the day of his death. Recalling death is a powerful device. “The final destination for all living things” as the grave is referred to in the book of Iyov, can remind the distracted person that life is more than just a game. There is a deadline, and there is much to accomplish in the meanwhile. Shlomo wrote, “It is far better to go to a house of mourning than a house of partying, since that is where all men will end up, and the living person ought to take this to heart”. There is a great deal to take to heart when death in contemplated. If nothing else works to help a person straighten out his life then thoughts of death are the Gemara’s last hope for him. First he is to try to simple harness his self-control and do the right thing. But if that proves too challenging, then his next step is Torah study, revisiting his values and principles and measuring the truth against his desires. If even that does not work, he thinks of Hashem’s unity, and his commitment to accepting the yoke of Divine commands, that the Shema represents. It is only after trying all of this that he then is exhorted to think of his day of death.
If thinking of the day of death is the most powerful catalyst for a struggling fellow, then we have to question why this is only a last resort? Wouldn’t a doctor offer the most reliable cure as a first resort to his patients?
R. Shimon Greenfield, the Maharshag (1860-1930), addressed this issue. In explaining the Gemara’s reluctance to have a person contemplate the day of his death, he explained that the proper way to do mitzvos is with joy and deep happiness, and not out of fear or worry. The true way to serve Hashem is to ignore ones inadequacies and sins, and simple forge ahead, he says! It is only as a last resort that one should engage in morbid thinking, for though it may be an effective cure for ones misplaced urges is the moment, its side effects can be damaging. One is in danger of sinking into negative and depressive thinking when he spends too much time thinking about death. So the Gemara only allows one to do so after he has exhausted his other options.
This explains Maharshag is what our Midrash was attempting to teach. Due to the fact that Aaron and his children were singled out to be the constant servants of Hashem, serving in the temple and bringing the offerings, their job needed to be done with the utmost joy and passion. They would not be acting out of fear, or neurotic worry. So they were told to stay away from dead bodies, and the sort of thinking that this can engender. Since Aaron was possessed with the true pure fear of God, he was not in need of the extra encouragement that experiencing death can provide, and so he and his children could avoid the possible pitfalls of getting inspiration from something negative and morbid.
The Kohanim were of the tribe of Levi, they were the teachers of Torah. They are commanded to bless the Jewish people, out of love. You can only teach somebody something out of love and passion. Frightening your children into living a good life is a terrible idea. If you love what you are doing, it will pass along. “Hashem, make the words of the Torah sweet in our mouths, and then we and our children and their children will all know your name, and learn your Torah sincerely.” We don’t ask for pedagogic skill – we ask that the Torah be sweet in our mouths. If it is, then it will pass along. “One who loves the Rabbis,” says the Gemara, “will have children who are Rabbis.
Though there is a deep need for a measure of fear of God, and awe of Him in a person’s life, one must remember that the truest way to serve Hashem is with joy and passion. Teach your children and your neighbors about the positive messages of the Torah. Let them see the joy on your face. As the Torah tells us in our very parsha, “You shall keep my commandments and do them, I am Hashem. You shall not disgrace my name, but [rather] sanctify me in the eyes of other Jews.” Ksav Sofer cites the teaching of our sages, of how when someone studies Torah at a high level, he must then be meticulous in his dealings with others, so that people say “fortunate are his father and rabbi who taught him Torah,” for if he acts disgustingly with people, they will blame the Torah as well, “woe to his father and Rabbi who taught him Torah”. He explains that for this reason, the Torah mentions how one must appear in the eyes of others immediately after mentioning how meticulous one must be in his observance. To be a lesson for others requires one to be positive and pleasant. The Kohen can not be an ascetic Temple dwelling sort of priest, he has to be the teacher who looks at his flock with love, inspired by his experiences with life and goodness, and avoiding anything that can possibly get him down.
 Vayikra Rabbah 26:6
 Tehillim 19:10
 Brachos 5a
 Koheles 7:2
 Zehav Shva to Emor, s.v. emor. See also the comments of Techeles Mordechai (of Maharsham) to Emor no. 4, (p. 1054 in Daas Torah ed.) on this Midrash where he explains that since overexposure to death causes a person to be desensitized to death, a Kohen must avoid this, and thus our sages also were reluctant to advise this as a first resort since it is to be used sparingly if it is to work.
 Shabbos 23b
 See Shabbos 31a, where the amount of fear of God that must be present is compared to a kav. Perhaps the reason it is describes a limited measure is because too much of a focus on engendering fear is actually not conducive to proper divine service.
 Vayikra 22:31-31
 To Emor, ad loc
 Yoma 86a