Emma Jung and Marie-Louise von Franz have produced a very comprehensive analysis of the legend of the Holy Grail legend. Jung spent over 20 years collecting the background information. Von Franz spent 15 years pulling together the final manuscript which was published after Emma Jung's death.
The book explores the historic origin of the legend in both Welsh/Celtic and Christian legend. The legend appears to integrate 3 influences: the legends of the early Welsh/Celtic people who were driven into the hills by the Saxon invaders, the Christian legend of the grail and the stone covering the grave of Christ, and the major shift in Western consciousness regarding the role of women around the reign of Henry II and Eleanor of Acquitaine.
The story is about the heroic actions and adventures of the fool knight, Perceval, that are needed to heal the wounded Fisher King and revive his famine plagued kingdom. Much of the book explores all the images and multiple variations around this myth.
The legend would imply that in all men a wounded Self(Fisher King) limits and shuts off the powers and creativity of the archetypes and other unconscious forces. The healed Fisher King is a strong Self, the king of the unconscious, who can navigate and attract unconscious forces and influences. The beautiful woman, the Anima, acts as a messenger between the ego consciousness and the unconscious. The Grail is the site where the opposites are united, the personality becomes whole,the internal struggles against opposing forces within the self stops, and thus the healing of the King (Self) is at hand. Each of the psychological constructs: ego, consciousness, unconscious, archtype, shadow, anima, animus, Self, etc. are shown in the characters and various props/objects within the legend.
Students of the legends of King Arthur and the Round Table will find this to be a very scholarly study of the particular tale of Perceval and his search of the Holy Grail. The Round Table is connected to the two preceeding tables - the table where Christ held the Last Supper with his disciples and the table that becomes the Altar for the Holy Communion.
Students of pre-Saxon Britian will find this work to identify multiple primitive Celtic and Welsh myths and legends.
Students of Jung will find this legend actually is able to encompass almost all the major constructs of Jungian theory into one comprehensive legend. Jung identifies the Self as the part of the personality through whom God speaks. This makes sense if we see the Self as the king of the unconscious, a land of symbol and archetype. If the Self is wounded, the land of archetype and symbol is barren and thus the voice of God is not heard. But when the Self is healed, God is able to speak through the language of image, myth, archetype, and symbol. The heroic knight is able to heal the wounded King by asking whom the Grail serves. The Grail is the site where opposing forces are united and integrated and thus tension and internal conflict is reduced or eliminated. Jung and von Franz also point out that the Grail, the stone over the grave of Christ, the philosopher's stone, and the legendary figure of Merlin all are capable of playing the role of the site where the opposites come together to bring about wholeness. When wholeness occurs, the Fisher King is healed. When the Fisher King (the Self) is healed, the land is no longer barren but bursts with growth of instincts, symbols, myths, images, archetypes, allowing God to come fully into the personality. This is called salvation in Christian culture and enlightenment in other cultures. Carl Jung offers an amazingly rich theoretically constructed human personality with such internal consistency that he was able to explain most all human ocnditions from mental illness to religious salvation using his constructs.
I recommend this book highly, supplement your reading with other books by Carl Jung as you read, but your quest for your own Holy Grail is worth the effort.