It is not necessary to dwell on these sources of error, for they are probably apparent to all; and to give illustrative cases would be superfluous, and perhaps invidious. But it is important to observe that stories so improved, whether from a desire to reinforce some theological tenet, or from the mere love of sensation, are apt to betray their origin in many different ways. Narrators of this kind rarely content themselves with the finer touches; the added ornaments are apt to be gross and palpable; the "spirit" will be made to speak words of warning or comfort; to intimate his testamentary dispositions; or even--in somewhat bolder flight of fancy--to leave a solid memento behind him. Now the authentic phantom is seldom either dramatic or edifying. _Errors of Memory._ More insidious and more difficult to guard against are errors of memory. There is a natural and almost inevitable tendency to dramatic unity and completeness which leads to the unconscious suppression of some details, and the insertion of others. Probably of all errors due to this cause a nice adjustment of the dates is the commonest. In perhaps the majority of second-hand cases, and in some of the more remote first-hand narratives, the coincidence is said to be exact to the minute. "_At that very moment my friend passed away_" is a common phrase. As a matter of fact, in the best attested recent cases it can rarely be shown that the coincidence is precise, and the impression frequently follows the death by some hours. But there is risk also of the actual transformation of the experience itself. A dream after the lapse of years will be recalled as a hallucination,[75] a vague feeling of discomfort as a vivid emotion, or even a mental vision; a hallucination not recognised at the moment will in the retrospect seem to have been identified with some person who died at about that time; and details, such as clothes worn or words spoken by the phantom, will be borrowed from later knowledge and read back into the image preserved in the memory. There will further be a gradual simplifying and rounding off of the incident, a deepening of the main lines, and a suppression of what is not obviously relevant or coherent. With many persons there can be no doubt that this process is almost, if not wholly, unconscious; and it need hardly be said that in that very fact lies the special danger against which we have to guard.[76]