Brewster says, when treating of this subject, that there can be little doubt that the concave mirror was the principal instrument used in connexion with the pretended apparitions of the gods and goddesses in the ancient temples. In the meagre history of these apparitions that has come down to us, we can easily perceive the traces of an optical illusion. In the ancient temple of Hercules at Tyre, there existed a certain seat made of consecrated stone, out of which the gods rose, apparently at the will of the priests. Æsculapius appeared frequently to his worshippers in his temple in Tarsus, and the temple of Eugenium was famous for the number of gods and goddesses which were constantly visiting its sacred precincts. Iamblicus tells us that the priests showed the gods to the people in the midst of smoke; and when the great magician Marinus terrified his auditory by suddenly showing them the statue of Hercules in the midst of a cloud of incense, it was undoubtedly a woman who performed the part, dressed up in man’s robes for the occasion. The character of these spectacles in the ancient temples is admirably described by Damasius, and there is no difficulty in seeing that optical illusions were the means employed to delude the audience. He describes the apparition on the wall of a large spot of white, which at first appeared at a distance, but gradually came nearer and nearer until at last it assumed the form of a divine or supernatural being, of severe yet mild aspect and of great personal beauty. This being the Alexandrians immediately honoured as Osiris or Adonis. Amongst more modern examples of this illusion may be mentioned that of the Emperor Basil of Macedonia. Inconsolable at the loss of his son, this potentate had recourse to the prayers of the Pontiff Theodore Lantabaren, who was celebrated for his power of working miracles. The conjurer showed the Emperor the image of his dead son magnificently attired and mounted on a splendid war-horse. The young man dismounted, and, going up to his father, threw himself into his arms and disappeared. Salvertius, in speaking of this story, observes judiciously, that the deception could only take place through the agency of some person who closely resembled the Emperor’s son, and that the trick would have been easily discovered when the person embraced the Emperor. A better explanation of the affair is, however, afforded by supposing that the Emperor saw an aërial image of a person resembling his son, and that when he rushed forward to embrace him it disappeared. The accounts of the operations of the ancient magicians are too meagre to give us any idea of the splendour of some of these ancient ceremonies. A system of deception such as this, employed as a means of government, must have brought into requisition not only the talents of all the learned men of the day, but a crowd of accessories calculated to astonish and confound the judgment, fascinate the senses, and facilitate imposture.