Here, for instance, is a traveller who, arriving at night in a small unknown town and walking along the ill-lighted dock in the direction of an hotel of which he roughly knows the position, at a given moment feels an irresistible impulse to turn and go the other way. He instantly obeys, though his reason protests and “berates him for a fool” in taking a roundabout way to his destination. The next day he discovers that, if he had gone a few feet farther, he would certainly have slipped into the river; and, as he was but a feeble swimmer, he would just as certainly, being alone and unaided in the extreme darkness, have been drowned.[21] But is this a prevision of an event? No, for no event is to take place. There is simply an abnormal perception of the proximity of some unknown water and consequently of an imminent danger, an unexplained but fairly frequent subliminal sensitiveness. In a word, the problem of the future is not raised in this case, nor in any of the numerous cases that resemble it. Here is another which evidently belongs to the same class, though at first sight it seems to postulate the preexistence of a fatal event and a vision of the future corresponding exactly with a vision of the past. A traveller in South America is descending a river in a canoe; the party are just about to run close to a promontory when a sort of mysterious voice, which he has already heard at different momentous times of his life, imperiously orders him immediately to cross the river and gain the other shore as quickly as possible. This appears so absurd that he is obliged to threaten the Indians with death to force them to take this course. They have scarcely crossed more than half the river when the promontory falls at the very place where they meant to round it.[22] The perception of imminent danger is here, I admit, even more abnormal than in the previous example, but it comes under the same heading. It is a phenomenon of subliminal hypersensitiveness observed more than once, a sort of premonition induced by subconscious perceptions, which has been christened by the barbarous name of “cryptaesthesia.” But the interval between the moment when the peril is signalled and that at which it is consummated is too short for those questions which relate to a knowledge or a preexistence of the future to arise in this instance. The case is almost the same with the adventure of an American dentist, very carefully investigated by Dr. Hodgson. The dentist was bending over a bench on which was a little copper in which he was vulcanizing some rubber, when he heard a voice calling, in a quick and imperative manner, these words: “Run to the window, quick! Run to the window, quick!” He at once ran to the window and looked out to the street below, when suddenly he heard a tremendous report and, looking round, saw that the copper had exploded, destroying a great part of the workroom.[23]