She then remembered that the book in which it was found had been in her room for some hours the day she received her father's letter. What happened, I have no doubt, was that she absentmindedly slipped the check into the book, and then, so far as her upper consciousness was concerned, forgot all about it. But subconsciously she would remember and subconsciously would be reminded of it the day before the dream when, in the college library, she happened to see the same book again, without, perchance, any conscious knowledge of seeing it. That night, in sleep, her mind busied itself once more with the problem of the missing check, this time to good purpose. Very similar is a dream for which I am indebted to Mr. Andrew Lang, who got it from the dreamer, an English lawyer. This gentleman had sat up late to write letters, and about half-past twelve went out to post them. On his return he missed a check for a large amount received by him during the day. He searched everywhere in vain, went to bed, and soon fell asleep. Then he dreamed that he saw the check curled around an area railing not far from his own door. Waking, he was so impressed that, although it was not yet daylight, he got up, dressed, walked out of the house, and found the check at the spot indicated by his dream. In another case a Californian, visiting in Sullivan County, New York, lost a gold ring given him by his sister. That night he dreamed he saw it lying in the sand beneath a swing, in which he had been sitting in the afternoon. It was actually there, as he ascertained by looking next day. Similarly, a clerk in a customs house recovered a valuable document, the loss of which would have cost him his position. And the wife of a clergyman, the Reverend W. F. Brand, of Emmorton, Maryland, had revealed to her in a dream the hiding-place of a sum of money which, six months before, she had put away at her husband's request, but had afterward accidentally slipped into a bundle of shawls. Decidedly, we not only see more than we are aware of, but we also remember more and for a far longer time than is usually supposed. Which brings me to another point of great importance to the student of clairvoyance and other psychical problems, and also, as will appear in a later chapter, of tremendous significance in affairs of everyday life. The tenacity of memory is such that nothing one sees is really forgotten. It merely slips, as it were, into some subterranean region of the mind, whence, days and months and even years afterward, it may be recalled. Of this we have incontrovertible proof in the phenomena of crystal-gazing, a species of clairvoyance in which, by gazing into a crystal or a glass of water, or any small body with a reflecting surface, it is sometimes possible to perceive hallucinatory pictures of people and places situated far beyond the gazer's normal field of vision, and occasionally depicting events occurring at the moment they are seen in the crystal.