what is the significance of this quote “…they were a satisfactory hint of the unreality of reality, a promist that the rock of the world was founded securely on a fairy’s wing.”

Gatsby holds on to a reality that doesn't exist. His unreality becomes his reality if only he will spend enough money and somehow will his way back in time, back to when he was with Daisy. There is of course a chance that he might woo Daisy back but things can never be like what they were before. Whatever Gatsby was hanging seemed in reach but never graspable.