The Chasam Sofer (Rabbi Moshe Sofer of Preshburgh) ztvk"l explains this passage allegorically. Hashem's ways are hidden from us and often we cannot understand that they are really beneficial.

When, for example, King Achashverosh killed his wife Vashti, took Ester to be his Queen and elevated the evil Haman to the highest position in his government, the Jews could only perceive tragedy coming their way.

It was only years later, when the Purim story unraveled completely, that they were able to understand, in retrospect, how every piece fit perfectly into the puzzle of redemption for the Jewish People.

This is what Hashem alluded to when He said "you will see My back, but My face may not be seen." Hashem's ways can be understood only with hindsight; not when one is still within the picture looking forward to what will be.

However, although we cannot see what will transpire until after the fact; we are expected to believe that everything Hashem does is for the good, even when we cannot yet understand exactly how and why things are happening.

In his book Aleinu Leshabeach, Rabbi Zilbershtein shlita tells a fantastic story which occurred in New York many years ago.

Reb Moshe Daikman, the president of the Slonimer Yeshiva in the USA, was a very rich philanthropist who always gave charity with an open hand. The basement of his home served as his jewelry center, from where he sold precious stones to his many customers.

One day, he was visited by some municipality workers who explained that they were sent to inspect the safety of his edifice. It was the first time such an inspection had taken place and it came as a big surprise. The inspectors went from room to room and from floor to floor and found no irregularities except for one. There was an emergency exit from the basement which consisted of a ladder which, of course, was never used. This ladder was positioned vertically, rather than on a slant, which would have made it difficult to use in times of a real emergency, G-d forbid.

Reb Moshe, who was surprised at the visit, was even more surprised that they made such a big deal about what seemed to be a minor detail and was a common occurrence in many work places. But what was most amazing was that they told him that they would return in 48 hours and fine him heavily if it were not dealt with properly.

Having not been left with much choice, Reb Moshe summoned a worker that very day to reposition the ladder according to the legal requirements.

The very next morning two fellows knocked on his door and said that they wanted to buy some jewelry. They did not look at all suspicious, and so Reb Moshe went down to the basement with them. However, they quickly overcame the elderly gentleman; tied his hands and lay him down on the floor. After taking merchandise worth hundreds of thousands of dollars, they speedily fled; after cutting all of the telephone wires and locking all of the doors leading to the basement.

Reb Moshe tried to free his hands from their bonds but was not successful. With great difficulty he succeeded to stand on his feet but he soon discovered that all of the exits were locked. Suddenly he remembered the emergency exit; something he might not even have thought of except for the unexpected visit the day before which had brought it to his attention. As he approached the ladder he realized that were it standing straight, he would never have been able to ascend it, since his hands were tied. However, since it was now standing on a slant, he was able to free himself with only a little difficulty.

Only then, did everyone understand the strange events of the day before. With 20-20 hindsight, Reb Moshe and his friends contemplated what could have been the sad ending had not Hashem sent the cure before the ailment.