A later factor in the predilection for the red, orange and yellow rays, though scarcely a factor in their discrimination, lies in the fact that these are the colors of fire. Flame, apart from its beauty, on which certain poets, Shelley especially, have often insisted, is a source of massive physical satisfaction. Even under the conditions of civilization we are often acutely sensitive to this fact, while under the conditions of primitive life, in imperfect shelters, caves or tents, where no other source of artificial light and heat is known, the satisfaction is immensely greater. At the same time fire is associated with food, it is a protection from wild beasts and the accompaniment of the festival. It may even take on a sacred and symbolic character, and the Roman goddess Vesta was, as Ovid said, simply ‘living flame.’ While fruit or fire would tend to make the emotional tone of red pleasant, another very powerful factor in its emotional influences, though this time as much by causing terror as pleasure, is the fact that it is the color of blood. That ‘the blood is the life’ is a belief instinctively stamped even on the emotions of animals, and it has not died even in civilized man, for the sight of blood produces on many persons a sickening and terrifying sensation which is only overcome by habit and experience or by a very strong effort of will. It is not surprising that in some parts of the world, and even in our own Indo-European group of languages, the name for red is ‘blood-color.’