“Ruin by elders—construction; construction by youths—ruin” (Megillah 31b).
Elders are those who are accustomed to the work of the Creator. Youths are those who are in the beginning of their work. “Ruin” means a descent or a fall, where previously they had some ascent in the work, which is regarded as building, meaning that they appreciated the ascent, but the ruin is when they felt some fall, which comes from the concealment of the Creator, that the Creator hides Himself from them. This is called “ruin.”
“Ruin by elders” means that they say that the Creator sent them the concealment. It follows that they are already building, since they believe that the Creator is tending to them, and from this they derive vitality.
Faith is apparent primarily during the descent, when it does not shine for a person. At that time, he faces a dilemma: Either he says, “I do not need any benefits. Rather, I want to bring contentment above and I do not care what I feel,” or it is otherwise.