As Jonas descended into the belly of the whale so does psychic energy descend into the darker spheres of the unconscious at certain times in life.
With this descent, the ego loses all outer orientation and experiences profound hopelessness, even the darkness of despair.
Jung calls this passage The Night Sea Journey. He himself lived his journey in 1913, when feeling the hopelessness of a lost orientation, he resorted to plunging into the inner realms of his own psyche.
The Night Sea Journey is a psychic event. We may translate it as depression, but something is actually happening in the psyche that remains a mystery for the ego.
This presentation is about discovering the mystery and participating in its intention. It helps us give meaning to these times of disorientation and even be conscious of the outcome and eventual graces accompanying the return.