seeing the future have never been without their sceptical critics. Aristotle carried out an inquiry into allegedly prophetic dreams in his On Divination in Sleep. He accepted that "it is quite conceivable that some dreams may be tokens and causes [of future events]" but also believed that "most [so-called prophetic] dreams are, however, to be classed as mere coincidences...". Where Democritus had suggested that emanations from future events could be sent back to the dreamer, Aristotle proposed that it was, rather, the dreamer's sense impressions which reached forward to the event. 17th–19th centuries The term "precognition" first appeared in the 17th century but did not come into common use among investigators until much later. An early investigation into claims of precognition was published by the missionary Fr. P. Boilat in 1883. He claimed to have put an unspoken question to an African witch-doctor whom he mistrusted. Contrary to his expectations, the witch-doctor gave him the correct answer without ever having heard the question. Early 20th century In the early 20th century J. W. Dunne, a British soldier and aeronautics engineer, experienced several dreams which he regarded as precognitive. He developed techniques to record and analyse them, identifying any correspondences between his future experiences and his recorded dreams. He reported his findings in his 1927 book An Experiment with Time. In it he alleges that 10% of his dreams appeared to include some element of future experience. He also persuaded some friends to try the experiment on themselves, with mixed results. He noted a strong cognitive bias in which subjects, including himself, were reluctant to ascribe their dream correspondences to precognition and determinedly sought alternative explanations. Dunne concluded that precognitive elements in dreams are common and that many people unknowingly have them.<ref>Flew, Antony; "The Sources of Serialism, in Shivesh Thakur (Ed). Philosophy and Psychical Research, George Allen & Unwin Ltd. 1976, pp. 81–96. </ref> He suggested also that dream precognition did not reference future events of all kinds, but specifically the future experiences of the dreamer. He was led to this idea when he found that a dream of a volcanic eruption appeared to foresee not the disaster itself but his subsequent misreading of an inaccurate account in a newspaper. Edith Lyttelton, who became President of the Society for Psychical Research (SPR), regarded his theory as consistent with her own idea of the superconscious. In 1932 he helped the SPR to