Without going into technical occult explanations, I would say that the virtue of these articles consists entirely of their associative value. That is to say, they carry in them certain vibrations of past experience which serve as a connecting link, or associated filament, with the thing which is sought to be brought into the field of clairvoyant vision. To reach clairvoyantly a thing, scene, or person in this way is akin to the unwinding of a ball of yarn, when you hold the loose end in your hand. Or, it is like giving a keen-scented dog a sniff at a handkerchief once carried by the person whom you wish him to nose out for you. A well-known authority on the subject of psychic phenomena has said on this point: "The untrained clairvoyant usually cannot find any particular astral picture when it is wanted, without some special link to put him en rapport with the subject required. Psychometry is an instance in point. It seems as though there were a sort of magnetic attachment or affinity between any particle of matter and the record which contains its history--an affinity which enables it to act as a kind of conductor between that record and the faculties of anyone who can read it. For instance, I once brought from Stonehenge a tiny fragment of stone, not larger than a pin's head, and on putting this into an envelope and handing it to a psychometer who had no idea what it was, she at once began to describe that wonderful ruin and the desolate country surrounding it, and then went on to picture vividly what were evidently scenes from its early history, showing that the infinitessimal fragment had been sufficient to put her into communication with the records connected with the spot from which it came. The scenes through which we pass in the course of our life seem to act in the same way upon the cells of our brain as did the history of Stonehenge upon that particle of stone. They establish a connection with those cells by means of which our mind is put en rapport with that particular portion of the records, and so we 'remember' what we have seen."