The mystery.

Maybe a mentally healthy person has a sufficient amount of mystery in thier life, a sort of potential held within a person for what is awe-ful — what is full of awe — about their existence. Perhaps there is a need for room for a meaningful and real transcendence in a persons life.

Maybe the reality shown by reason is not as important to a mental health as the truth shown by what is proven to be outside of argumentative reasoning.