Iamblichus also undertakes the defense of theurgy and carefully distinguishes it from magic, as we shall soon see. It is also different from science, since it does not merely employ the physical forces of the natural universe,[1380] and from philosophy, since its ineffable works are beyond the reach of mere intelligence, and those who merely philosophize theoretically cannot hope for a theurgic union or communion with the gods.[1381] Even theurgists cannot as a rule endure the light of spiritual beings higher than heroes, demons, and angels,[1382] and it is an exceedingly rare occurrence for one of them to be united with the supramundane gods.[1383] This theurgy, or “the art of divine works,” operates by means of “arcane signatures” and “the power of inexplicable symbols.”[1384] It is thus that Iamblichus explains away most of the details in sacred rites and sacrifices to which Porphyry had objected as obscene or material and as implying that the gods themselves were passive and passionate. They are mystic symbols, “consecrated from eternity” for some hidden reason “which is more excellent than reason.”[1385] Occult virtues indeed! We have already heard Iamblichus state that natural objects participate in or are related to the gods etherially or aerially or aquatically; theurgists therefore quite properly employ in their art certain stones, herbs, aromatics, and sacred animals.[1386] By employing such potent symbols mere man takes on such a sacred character himself that he is able to command many spiritual powers.[1387] [Sidenote: Invocations and the power of words.] Invocations and prayers are also much used in theurgical operations. But such invocations do not draw down the impassive and pure gods to this world; rather they purify those who employ them from their passions and impurity and exalt them to union with the pure and the divine.[1388] These prayers are symbolic, too. They do not appeal to human passions or reason, “for they are perfectly unknown and arcane and are alone known to the God whom they invoke.”[1389] In another passage[1390] Iamblichus replies to Porphyry’s objection that such prayers are often composed of meaningless words and names without signification by declaring—somewhat inconsistently with his previous assertion that these invocations are “perfectly unknown”—that some of the names “which we can scientifically analyze” comprehend “the whole divine essence, power and order.” Moreover, if translated into another language, they do not have exactly the same meaning, and even if they do, they no longer retain the same power as in the original tongue. We shall meet a similar passage concerning the power of words and divine names in the church father Origen who lived earlier in the third century than Porphyry and Iamblichus. Iamblichus concludes that “it is necessary that ancient prayers ... should be preserved invariably the same.”[1391] [Sidenote: Magic a human art: theurgy divine.]