89. Certain spirit manifestations lend themselves quite easily to being imitated, but even though they may be exploited like so many other phenomena by means of trickery and sleight-of-hand, it would be absurd to conclude that they do not actually exist at all. For anyone who has studied and knows the normal conditions under which they may be produced, it is easy to tell an imitation from an authentic manifestation. Furthermore, an imitation could never be complete and could deceive only unknowing observers incapable of understanding the characteristic nuances of authentic phenomena.
90. The manifestations easiest to imitate are certain physical effects and common intelligent effects, such as movements, raps, apportations, direct writing, banal responses, etc. The same does not apply to intelligent communications of a high level. To imitate the former, only skillfulness is required; to simulate the latter, an uncommon erudition, exceptional intellectual abilities and a comprehensively broad — so to speak - faculty of improvisation would be necessary.
91. Persons who are unfamiliar with Spiritism may be led to suspect the good faith of mediums; study and experience provide them, the means of assuring themselves of the authenticity of the phenomena. Additionally, the best guarantee lies in the medium's absolute disinterest and honorability. There are persons who, because of their position and character, are beyond any suspicion. If the possibility of material gain, can encourage fraud, common sense would indicate that where there is nothing to gain, charlatanism has nothing to do.
92. We may find both enthusiasts and eccentrics among Spiritism's adherents - as in everything else. They are usually the worst propagators because the ease with which they accept everything without an in-depth examination arouses distrust. Knowledgeable Spiritists are on their guard against blinding enthusiasm and observe everything coolly and. calmly. This is the way not to fall victim to either illusions or deceptions. Besides the issue of good faith, beginning observers should, before anything else, take into consideration the seriousness of the character of the persons they address.