Is a divine being _compelled_, Porphyry asks, to aid in these
efforts, or is it only the soul of the seer, as some believe, which
hallucinates itself, by the aid of points de repere? {70b} Or is
there a blending of the soul's operations with the divine
inspiration? Or are demons in some way evolved out of something
abstracted from living bodies? He seems to hint at some such theory
of 'exuvious fumes' from the 'circle,' as more recent inquirers have
imagined. The young appear to be peculiarly sensitive to vapours,
invocations, and other magical methods, which affect the human
constitution, and the young are usually engaged as seers. Hence
visions are probably subjective. Ecstasy, madness, fasts and vigils
seem particularly favourable to divination. Or are there certain
mystic correspondences in the nature of things, which may be
detected? Thus stones and herbs are used in evocations; 'sacred
bonds' are tied (as in the Eskimo hypnotism and in Australia);
closed doors are opened, the heavenly bodies are observed. Some
suppose that there is a race of false and counterfeiting spirits,
which, indeed, Iamblichus admits. These act the parts of gods,
demons, and souls of the dead. Again, the conjurer plays on our
expectant attention. Omitting some remarks no longer appropriate,
Porphyry asks what use there is in chanting barbarous and
meaningless words. He is inclined to think that the demon, or
guardian spirit of each man is only part of his soul,--in fact his
'subliminal self'. And generally, he suspects that the whole affair
is 'a mere imaginative deceit, played off on itself by the soul'.

Replying as to divination, Iamblichus says that the right kind of
dreams are between sleeping and waking when we hear a voice giving
directions. A modern example occurred in the trial of the Assynt