In these perplexities, Porphyry resembles the anxious spiritualistic inquirer.  A ‘materialised spirit’ alleges himself to be Washington, or Franklin, or the lost wife, or friend, or child of him who seeks the mediums.  How is the inquirer, how was Porphyry to know that the assertion is correct, that it is not the mere ‘boasting’ of some vulgar spirit?  In the same way, when messages are given through a medium’s mouth, or by raps, or movements of a table, or a planchette, or by automatic writing, how (even discounting imposture) is the source to be verified?  How is the identity of the spirit to be established?  This question of discerning spirits, of identifying them, of not taking an angel for a devil, or vice versa, was most important in the Middle Ages.  On this turned the fate of Joan of Arc:  Were her voices and visions of God or of Satan?  They came, as in the cases mentioned by Iamblichus, with a light, a hallucination of brilliance.  When Jean Brehal, Grand Inquisitor of France, in 1450-1456, held the process for rehabilitating Joan, condemned as a witch in 1431, he entered learnedly into the tests of ‘spirit-identity’. {66a} St. Theresa was bidden to try to exorcise her visions, by the sign of the Cross.  Saint or sorcerer? it was always a delicate inquiry.

Iamblichus, in his reply to Porphyry’s doubts, first enters into theology pretty deeply, but, in book ii. chap. iii. he comes, as it were, to business.  The nature of the spiritual agency present on any occasion may be ascertained from his manifestations or epiphanies.  All these agencies show in a light, we are reminded inevitably of the light which accompanied the visions of Colonel Gardiner and of Pascal.  Joan of Arc, too, in reply to her judges, averred that a light (claritas) usually accompanied the voices which came to her. {66b} These things, if we call them hallucinations, were, at least, hallucinations of the good and great, and must be regarded not without reverence.  But modern spiritualistic and ghostly literature is full of lights which accompany ‘manifestations,’ or attend the nocturnal invasions of apparitions.  Examples are so common that they can readily be found by any one who studies Mrs. Crowe’s Night Side of Nature, or Home’s Life, or Phantasms of the Living, or the Proceedings of the Psychical Society.  Meantime Homer, and Theocritus in familiar passages, attest this belief in light attendant on the coming of the divine, while the Norse Sagas, and the well-known tale of Sir Charles Lee’s daughter and the ghost of her mother (1662), speak for the same belief in the pre-Christian north, and in the society of the Restoration. {67a} A light always comes among the Eskimo, when the tornak, or familiar spirit, visits the Angekok or sorcerer.  Here, then, is harmony enough in the psychical beliefs of all time, as when we learn that lights were flashed by the spirits who beset the late Rev. Stainton Moses. {67b} Unluckily, while we have this cloud of witnesses