The Night Sea Journey / Long Night Journey

   (re: picture)     Coming now to the psychology of the picture, it is clearly a descent into the unconscious.  The immersion in the bath is another “night sea journey,” …  TPofT 83

Just as, in the primitive myths, it is so stiflingly hot in the belly of the whale that the hero loses his hair, so the philosophers suffer very much from the intense heat during their confinement.  TPofT 83

The night sea journey is a kind of descensus ad inferos – a descent into Hades and a journey to the land of ghosts somewhere beyond this world, beyond consciousness, hence an immersion in the unconscious.