“The eye needs color as it needs light. We may recall our feeling of refreshment when the sun breaks through the clouds to flood a part of the landscape with light and make its colors visible. The belief that colored jewels have healing powers may be a result of the deep feelings aroused by this inexpressible delight.”

—Johann Wolfgang von Goethe, from his Farbenlehre, or Theory of Color, 1808. Translated and edited Douglas Miller, 1988.