Is President Monson a Chicken? (Or an Egg?)

In this morning's session of conference, President Monson mentioned that he was called to be a bishop at the age of 22. I knew he had served in a lot of positions at early ages, but this still surprised me. He was also called as a counselor in a stake presidency at 27, a mission president at around 32, and an apostle at age 36.

This made we wonder: Was President Monson called to such positions at such early ages because he is such a great man, or is he a great man because of his unique opportunities of service and leadership?

Perhaps it is some of both.