"And every day there were what we called 'the Green Hills'; that is, the low line of Castlereagh Hills which we saw from the nursery windows. They were not very far off but they were, to children, quite unattainable. They taught me longing--Sehnsucht; made me for good or ill, and before I was six years old, a votary of the Blue Flower." --C. S. Lewis, Surprised by Joy
The Blue Flower (German: Blaue Blume) is a central symbol of Inspiration. It stands for desire, love, and the metaphysical striving for the infinite and unreachable. German author Novalis first used the symbol in his unfinished Bildungsroman, entitled Heinrich von Ofterdingen. After contemplating a meeting with a stranger, the young Heinrich von Ofterdingen dreams about blue flowers which call to him and absorb his attention. In some cultures, blue roses traditionally signify a mystery, or attaining the impossible, or the neverending quest for the impossible. They are believed to be able to grant the owner youth or grant wishes.
Delphinidin is an anthocyanidin, a primary plant pigment, and also an antioxidant. Delphinidin gives blue hues to flowers like violas and delphiniums. It also gives the blue-red color of the grape that produces Cabernet Sauvignon, and can be found in cranberries and Concord grapes as well as pomegranates. --Wikipedia