Feel like there's injustice in the world?

I love this story about impatience told by Richard Wurmbrand, quoted in John Piper's Future Grace with his commentary following.

A legend says that Moses once sat near a well in meditation. A wayfarer stopped to drink from the well and when he did so his purse fell from his girdle into the sand. The man departed. Shortly afterwards another man passed near the well, saw the purse and picked it up. Later a third man stopped to assuage his thirst and went to sleep in the shadow of the well. Meanwhile, the first man had discovered that his purse was missing and assuming that he must have lost it at the well, returned, awoke the sleeper (who of course knew nothing) and demanded his money back. An argument followed, and irate, the first man slew the latter. Where upon Moses said to God, "You see, therefore men do not believe you. There is too much evil and injustice in the world. Why should the first man have lost his purse and then become a murderer? Why should the second have gotten a purse full of gold without having worked for it? The third was completely innocent. Why was he slain?"

God answered, "For once and only once, I will give you an explanation. I cannot do it at every step. The first man was a thief's son. The purse contained money stolen by his father from the father of the second man, who finding the purse only found what was due him. The third was a murderer whose crime had never been revealed and who received from the first the punishment he deserved. In the future believe that there is sense and righteousness in what transpires even when you do not understand."

Moses' impatience with God in this story would surely be overcome if he had more faith in God's power and wisdom to turn all things for the good of his people. God has promised again and again in the Bible to do just that (2 Chronicles 16:9; Psalm 23:6; 84:11; Jeremiah 32:40-41; Isaiah 64:4; Romans 8:28, 32; 1 Corinthians 3:22-23). In fact, the only thing misleading in this legend is the comment put in the mouth of God that, "For once and only once, I will give you an explanation." The fact is, God has given us explanations like this repeatedly in the Bible with enough illustrations to fill a book.