Even people who are especially gifted in the mediumistic line (they are talking about you, @Harte ) have only attained a partial success that is getting lost sooner or later. But people like these are very often struck by different diseases such as weakness of the eyes, nervous disturbances (your sleep paralysis), etc. The main reason for such ailments can be found in the fact that the clairvoyance has not been produced as a result of the mental or astral development, but has been conjured up by force and therefore is one-sided and morbid. Following any of those incompetent instructions leads without exception to an unnatural, morbid neutralization of an element that will result in an over-sensitivity of one of the sense organs. Consequently it is not impossible that in this manner perceptions from the astral and mental worlds may takeplace, but all these effects depend on the spiritual intelligence of the exercising person, on the maturity, and on the karma too. The neutralization of an element can be divided into fourmain groups: