The manifestations here touched upon are much more frequent in dark _séances_ than in the light; and even when some degree of illumination is allowed the usual practice is to provide “cabinets” or screens under the cover of which the psychical effects are developed. This naturally gives ample opportunity for trickery to persons who, whether for money-making or for other motives, pose as mediums without having any real qualifications for the work; and it is unquestionable that many instances of sham materialisations have from time to time taken place. On the other hand, the well-evidenced instances of real materialisations and of many other analogous kinds of psycho-physical phenomena are much more numerous. We must consider, moreover, that a good reason exists for dim light and darkness in connection with attempts to communicate with discarnate spirits. When the eyes are active the mind receives continual impressions of numerous objects and occurrences that engage its attention and render it much less receptive of occult influences. Hence by minimising or shutting out the distractions of sight the soul of a sitter becomes very much more attuned to whatever telepathy may exist in connection with such external spirits as are present. With regard to communicating in general the old proverb, “Practice makes perfect,” holds good. Mediums, it is true, are born, not made; but, as is the case with all human beings, their powers are at first immature, and have to be developed by long-continued exercise and more or less skilled training before the best results become attainable. Every person who wishes to speak with the dead is--as is also every other person in the world--at least a potential medium so far as he or she knows at the outset. If it be found on trial that psychic powers exist to an appreciable extent it may be taken for granted that they are capable of very great increase by persevering effort and systematic employment; and the growth may be such as to lead through the lower to the higher forms of communicating. If, however, after repeated experiments it appears that a susceptibility to psychical influences is lacking or very moderate in degree, or if, for any other reason, a continuance of personal effort be not desirable, then it becomes necessary to have recourse to the services of mediums. These latter may be either amateur or professional; but, whichever they are, their utility depends upon the stage of development they have reached.