This immunity of the true philosopher and sincere follower of truth from magic received illustration, according to Porphyry,[1336] in the case of Plotinus himself, who suffered no harm from the magic arts which his enemy, Alexandrinus Olympius, directed against him. Instead the baleful defluxions from the stars which Olympius had tried to draw down upon Plotinus were turned upon himself. Porphyry also states[1337] that Plotinus was aware at the time of the “sidereal enchantments” of Olympius against him. Incidentally the episode provides one more proof of the essential unity of astrology and magic. [Sidenote: Invoking the demon of Plotinus.] Plotinus, indeed, was regarded by his admirers as divinely inspired, as another incident from the _Life_ by Porphyry will illustrate.[1338] An Egyptian priest had little difficulty in persuading Plotinus, who although of Roman parentage had been born in Egypt, to allow him to try to invoke his familiar demon. Plotinus was then teaching in Rome where he resided for twenty-six years, and the temple of Isis was the only pure place in the city which the priest could find for the ceremony. When the invocation had been duly performed, there appeared not a mere demon but a god. The apparition was not long enduring, however, nor would the priest permit them to question it, on the ground that one of the friends of Plotinus present had marred the success of the operation. This man had feared he might suffer some injury when the demon appeared and as a counter-charm had brought some birds which he held in his hands, apparently by the necks, for at the critical moment when the apparition appeared he suffocated them, whether from fright or from envy of Plotinus Porphyry declares himself unable to state. [Sidenote: The rite of strangling birds.] This practice of grasping birds by the necks in both hands is shown by a number of works of art to have been a custom of great antiquity. We may see a winged Gorgon strangling a goose in either hand upon a plate of the seventh century B.C. from Rhodes now in the British Museum.[1339] A gold pendant of the ninth century B.C. from Aegina, now also in the British Museum, consists of a figure holding a water-bird by the neck in either hand, while from its thighs pairs of serpents issue on whose folds the birds stand with their bills touching the fangs of the snakes.[1340] There also is a figure of a winged goddess grasping two water-birds by the necks upon an ivory fibula excavated at Sparta.[1341] [Sidenote: Plotinus and astrology.]