345. In addition to invocations proper, spontaneous dictations offer innumerable subjects of study. They consist in waiting for whatever subject it may please the spirits to treat. Several mediums, in such cases, can work simultaneously. Sometimes an appeal may be made to a designated spirit ; more ordinarily those who choose to come are awaited, and often come in the most unexpected manner. These dictations may give rise to a crowd of questions whose theme is thus found already prepared. They should be scanned with care, to study all the thoughts they contain, and to judge if they bear the seal of truth. This examina tion, made with severity, is, as we have said, the best guarantee against the intrusion of deceiving spirits. From this motive, as well as for the instruction of the whole, knowledge of the communications obtained outside of the reunion should be given. There, as may be seen, lies an inexhaustible source of elements, eminently serious and instructive.