Carl Jung is the founder of Jungian psychology. This study recognized the reoccurrence of certain motifs throughout various cultures called archetypes. Another important concept in Jungian psycology is the collective unconscious and it's distinction from the more accepted personal unconscious.
Carl Jung's beliefs are a major inspiration for the NiGHTS series, and much of the series involves Jungian themes.
These are things that you are not consciously aware of, but can be, and know in some subconscious way, such as memories. The conscious and subconscious create nightopias and nightmares.
Collective unconscious describes subconscious inclinations and knowledge that all humans have, such as instincts. Jung also believed archetypes are a part of the collective unconscious. 
The Collective Unconscious has effects on nightopias and nightmares. It seems to unify Nightopia and Nightmare at large and into the Night Dimension as a whole. This allows Visitors to encounter Nightmarens based on other's fears or even allowing visitors to meet under unusual circumstances.
The Self is a very complex concept, it is totality of the psyche, unification of consciousness and unconsciousness in a person and all archetypes. It is a final stage of individuation, realizing a true personality. The Self unlike The Ego and The Shadow is transcendent, unchanging part of ourselves.
Carl Jung considered The Self as "God-image" within psyche, he described the encounter with The Self as the religious experience with God, having a feeling of numinousity: a feeling of euphoria and fear at the same time. The symbols of The Self are very complex and varied, representing in a symmetrical geometrical figures like mandalas or crystals, or figures of “supraordinate personality”, like religious figures like Buddha and Christ or Mana Personalities.
Though Jung associated The Self with divinity, but he also thought it is also a unity of opposites, like destruction and creation, meaning The Self had a dark side too, and Jung described it as most dangerous thing of all. Some can mistake The Self as the greater view of their ego, causing them to inflate their ideas regarding themselves, believing that God-like numinousity of The Self is their own personal magnificence, or The Self could destroy the healthy limits of the ego and cause people to spin megalomaniac. Jung considered a person should retain the ego when realizing The Self, though the ego is no longer the center of the identity.
The deleted boss, Selph, was supposed to represent The Self archetype.
The Mana Personality
The Mana personality is a personified archetypal image of supernatural force. Mana personality represents the great force and wisdom deep with our psyche, like all unconscious archetypes it can be projected onto others, like leaders and mythological/fictional characters. Mana personality could be considred as the first indication of The Self 
The male Mana Personality is Wise Old Man, the female one is The Great Mother.
Jung warned that possession by a Mana personality could cause megalomania, because it overtakes the conscious mind and ignore all reason, like a man possessed by Wise Old Man would think of himself as some sort of superman or great guru.
The Great Mother is the ideal, caring and loving person, she likes to help others and watch them grow. She protects others and preserves innocence. She represents kindess to others but also kindness to oneself. The negative aspect of The Great Mother is The Terrible Mother, she abuses others or smothers them with protective jealousy, The Terrible Mother is sometimes called The Witch, this may connect her to Bomamba.
The Senex can be a Wise Man; a mentor that helps people on their journeys, or perhaps a wise and noble leader. He can also be an old fool or a tyrant, somebody that is stuck in old ways, lacks curiosity or exerts cruel discipline, he may reject or even destroy innocence
Owl and Wizeman represent the Senex archetype.
The Eternal Child
The eternal child might be a perfect little angel or child hero, radiating innocence, playfulness and curiousity, representing freedom. In their negative aspects, they might be stubbornly rebellious and disrespectful to their elders, else they might be dependent and not able to think for themselves, they may depend on; or be looking for a saviour.
NiGHTS and Reala reflect the eternal child archetype.
The shadow represents hidden aspects of a person, repressed memories or flaws that somebody is in denial about. The shadow can also represent unrealized talents and capabilities that people are afraid of testing. Though dream images of The Shadow can look normal, they will still make a person feel uncomfortable around it.
NiGHTS and Reala reflect the shadow archetype.
A persona is a role or identity people take up, creating personas is fundamental to social interaction. For example, it is necessary to remain professional when working as a doctor. People sometimes create personas for fun or self-expression, as when roleplaying.
It is unhealthy to become a persona, this creates a shallow sense of self-worth that hinges on a specific thing.
The Persona is represented in the NiGHTS series by the Persona Masks, they represent the role of a loyal servant towards Wizeman.
- ↑ Jungian Psychology on Wikipedia
- ↑ Personal Unconscious on Wikipedia.
- ↑ Collective Unconscious on Wikipedia
- ↑ The Jungian concept of The Self on Wikipedia
- ↑ The Self
- ↑ Mana Personalities
- ↑ Journey of Dreams' Development
- ↑ Wise old man on Wikipedia
- ↑ NiGHTS states that Wizeman could be considered a father, and Wizeman uses Will's feelings of abandonment to invade his Nightopia.
- ↑ Eternal child on Wikipedia
- ↑ Shadow on Wikipedia
- ↑ Persona on Wikipedia