What is a mountain in life?

In the path of the ego's evolution, it is said we have three mounts to climb—the first is always one of worldly preferment—then we go down into the valley where all such things are taken from us except the lessons we have learned—then we climb the mental height and again are plunged into the valley—or have great mental ability, yet lack all opportunity to study—until finally with all these lessons impressed upon us we laboriously climb the spiritual height.

—The Teacher