The mind that thought of light, heavy, grey, yellow, still, swift, also conceived of magic that would make heavy things light and able to fly, turn grey lead into yellow gold, and the still rock into a swift water…
When we can take green from grass, blue from heaven, and red from blood, we have already an enchanter’s power—upon one plane; and the desire to wield that power in the world external to our minds awakes.
—J. R. R. Tolkien, “On Fairy-Stories”