The particular importance attributed to magic by the Mazdeans is a necessary consequence of their dualist system, which has been treated by us before.[74] Ormuzd, residing in the heavens of light, is opposed by his irreconcilable adversary, Ahriman, ruler of the underworld. The one stands for light, truth, and goodness, the other for darkness, falsehood, and perversity. The one commands the kind spirits which protect the pious believer, the other is master over demons whose malice causes all the evils that afflict humanity. These opposite principles fight for the domination of the earth, and each creates favorable or noxious animals and plants. Everything on earth is either heavenly or infernal. Ahriman and his demons, who surround man to tempt or hurt him,[75] are evil gods and entirely different from those of which Ormuzd's host consists. The magician sacrifices to them, either to avert evils they threaten, or to direct their ire against enemies of true belief, and the impure spirits rejoice in bloody immolations and delight in the fumes of flesh burning on the altars.[76] Terrible acts and words attended all immolations. Plutarch[77] mentions an example of the dark sacrifices of the Mazdeans. "In a mortar," he says, "they pound a certain herb called wild garlic, at the same time invoking Hades (Ahriman), and the powers of darkness, then stirring this herb in the blood of a slaughtered wolf, they take it away and drop it on a spot never reached by the rays of the sun." A necromantic performance indeed. {191}