Complete Works of Plutarch — Volume 3: Essays and Miscellanies
Chapter 71
These rods and the mock-suns are constituted of a double nature, a real subsistence, and a mere appearance;--of a real subsistence, because the clouds are the object of our eyes; of a mere appearance, for their proper color is not seen, but that which is adventitious. The like affections, natural and adventitious, in all such things do happen.