To dream of the Holy Grail represents wish fulfillment or a perfect solution. To search for the Holy Grail reflects your desire to find the perfect solution to something elusive.
Negatively, the holy grail in a dream may reflect dangerous behavior or risk taking to achieve an elusive goal. Obsession to the point of hurting yourself.
The Holy Grail in a dream is a sign that you want to find or discover something that has been lost or suppressed. Either a part of your personality or an answer that eludes you.