Chazal tell us that Kohanim are easily angered. Why is that so?
The answer is that “Kohanim zerizin hem” – kohanim by nature act with an emotional alacrity. And that’s because Kohanim have a very big responsibility. They are the designated Torah teachers – the spiritual leaders of Klal Yisroel. Now, that responsibility requires that they should respond quickly to every situation. They must be on constant guard to defend the Torah ideals. Because Avodas Hashem is so important to them, they are zerizim. They are all “bnei Torah and chareidim li’dvar Hashem.” That’s what Rashi says zerizim means (Shabbos 20a).
Now, when people are zerizim they can be zerizim for all good things – chesed, Torah, mitzvos. But once you are a zariz, your emotions are always on edge. Even though you are emotionally on edge to do good things, sometimes people misuse their emotional fervor and they become emotional and excited for wrong things as well. But Kohanim are not emotional for wrong things b’etzem. B’etzem they are emotional and excited for good things. That’s how they are supposed to use these emotions. But sometimes because of this emotional sensitivity, a Kohen will get angry. A Kohen might tell his wife, “I’m going to give you a get.” Now, he doesn’t mean it. He got overly excited. Therefore, the Gemara tells us that when a kohen gives a get it must be get mekushar, not a get pashut. A get mekushar you have to write one line and then sew it up. Then you write another line and sew it up. Hopefully, by the time you are almost done, he’s already cooled off and changed his mind. We want to give him a chance to cool off and change his mind.
But, it’s not because Kohanim should be getting angry for wrong things. Kohanim are zerizim – emotional zerizim. Hashem made them with a certain nervous excitement. But they can just as well use it for good things too. That’s really the purpose. Some tzadikim are full of nervous excitement to do good things. Not to do something that’s not good. It’s only that when you have that teva of a nervous excitement, you have to be careful that it should be used only in a good way.