V'Zot HaBracha(Deuteronomy 33-34)
The final verse of the Torah is a statement attesting to "the strong hand and the awesome power that Moses performed before the eyes of all Israel" (Deut. 34:12). What specifically was this "awesome deed" that Moses performed? Rashi tells us that upon seeing the idolatrous Golden Calf, Moses shattered the tablets of the Ten Commandments. It was the right thing to do at the time.
It is interesting that Moses is first introduced in the Torah with the story of his killing an Egyptian taskmaster who was beating a Jew. Notice that both the first thing the Torah tells us about Moses, and the last thing the Torah tells us about Moses, are incidents where he expresses anger.
Was Moses really prone to anger? We know that Moses was exceedingly righteous and humble. And actually God approved of these two acts. So what's the explanation?
The answer is that Moses had mastered the trait of anger, so that when he did express something that looked like anger, it was actually very deliberate and measured.
It's all an issue of control. If your child misbehaves and you start yelling, that's typically anger "out of control." But if your child is about to stick a fork into a light socket, you might decide to yell in order to impress upon him the degree of danger. In other words, one can express anger, without being truly "angry."
That's what Moses did. This behavior is even more amazing given a Midrash (quoted by the commentator, Tiferes Yisrael) which says that Moses was born with an inclination toward anger, but through working on himself was able to become master over it. And that, the Torah testifies, is truly "awesome."