A real figure seen under exceptional circumstances may at the time or in the light of subsequent events be regarded as a hallucination. Such a mistake is, as a rule, possible only out of doors; and the commonest form of it is when a figure is seen by the percipient resembling some friend believed to be at a distance, or in circumstances which make it difficult to suppose that the figure was of flesh and blood. A curious instance came under my notice recently. It was reported to me that a lady had seen in a certain provincial town the ghost of a friend at about the time of her death. The figure, accompanied by another figure, was seen in broad daylight at a distance of a few feet only; it was clearly recognised, and the proof of its non-reality lay in the complete absence of recognition in return. It was subsequently ascertained that the friend in question had actually been present in the flesh, with a companion, at the spot where the figures were seen, but that for sufficient reasons she desired to avoid recognition. Her death within a few days of the encounter was merely an odd coincidence. Another kind of erroneous inference is worth noting. Cases are not infrequently quoted, as presumably telepathic, of a dream or vision embodying information demonstrably not within the conscious knowledge of the percipient. The inference that he cannot have obtained the information by normal means is clearly unsound, unless it can be shown that it was impossible for the information to have been received unconsciously. For it is well established that intelligence, even of events closely affecting the percipient, may enter through the external organs of sense and lie latent for days before emerging into consciousness. It is obvious that, for instance, many of the cases quoted in which an invalid became aware of news (_e.g._, of the death of a relative) which had been studiously withheld from him by those around may be thus explained. Whispers heard in sleep, or hints unconsciously received, may have betrayed the secret.[73] _Errors of Narration._