between one kind of manifestation and another. Even Inquisitors
have differed in opinion.

Iamblichus next tackles the difficult question of imposition and
personation by spirits. Thus a soul, or a spirit, may give itself
out for a god, and exhibit the appropriate phantasmagoria: may
boast and deceive (ii. 10). This is the result of some error or
blunder in the ceremony of evocation. {69} A bad or low spirit may
thus enter, disguised as a demon or god, and may utter deceitful
words. But all arts, says our guide, are liable to errors, and the
'sacred art' must not be judged by its occasional imperfections. We
know the same kind of excuses in modern times.

Porphyry went on to ask questions about divination and clairvoyance.
We often ascertain the future, he says, in dreams, when our bodies
are lying still and peaceful: when we are in no convulsive ecstasy
such as diviners use. Many persons prophesy 'in enthusiastic and
divinely seized moments, awake, in a sense, yet not in their
habitual state of consciousness'. Music of certain kinds, the water
of certain holy wells, the vapours of Branchidae, produce such
ecstatic effects. Some 'take darkness for an ally' (dark seances),
some see visions in water, others on a wall, others in sun or moon.
As an example of ancient visions in water, we may take one from the
life of Isidorus, by Damascius. Isidorus, and his biographer, were
acquainted with women who beheld in pure water in a glass vessel the
phantasms of future events. {70a} This form of divination is still
practised, though crystal balls are more commonly used than
decanters of water. Ancient and modern superstition as in the
familiar case of Dr. Dee, attributes the phantasms to spiritual
agency