Cerberus by William Blake
In Greek mythology Cerberus was the terrifying, three-headed watchdog who guarded the entrance to the Underworld. In Hindu mythology Shri Bhairava, the aspect of the Divine who protects people from the denizens of the Underworld (the superego), has a dog as his vehicle.
The superego is the accumulated conditionings of years of human life. If the awareness goes too much into this region of the mind it becomes a hell. Superego is as much a danger to Self-realisation as the ego.