Gray
Gray can suggest something "old and gray," which in turn may imply wisdom (compare "Gandalf the Gray," the wise old man’s gray beard, and so on.). The lack of vibrant color gives the color a humble quality.
Gray, as an absence of color, can also signify depression—a state we might associate with gray weather, heavy gray clouds, general melancholy, and lack of emotion. (Colors usually evoke feelings.)
Furthermore, the gray’s lack of colors can symbolize a lack of distinction, that is, unconsciousness. A half-lit room or landscape appears in gray tones; “all cats are gray in the dark,” and so forth, there are no distinctions. As a situation nears consciousness (as light appears), the surroundings also become more colorful.
On the other hand, the lack of distinction in gray can also be a needed experience. Sunlight, which makes everything clear and easy to discern, symbolizes logos and the masculine principle. While this quality has its merits, our inner self may often yearn for its opposite—the unclear, gray, feminine moonlight; eros or yin.