Sri Aurobindo
Letters of Sri Aurobindo
9. Fate and Free-Will, Karma and Heredity, etc
About spiritism, I think, I can say this much for the present. It is quite possible for the dead or rather the departed – for they are not dead – who are still in regions near the earth to have communication with the living; sometimes it happens automatically, sometimes by an effort at communication on one side of the curtain or the other. There is no impossibility of such communication by the means used by the spiritists; usually, however, genuine communications or a contact can only be with those who are yet in a world which is a sort of idealised replica of the earth-consciousness and in which the same personality, ideas, memories persist that the person had here. But all that pretends to be communications with departed souls is not genuine, especially when it is done through a paid professional medium. There is there an enormous amount of mixture of a very undesirable kind – for apart from the great mass of unconscious suggestions from the sitters or the contributions of the medium’s subliminal consciousness, one gets into contact with a world of beings which is of a very deceptive or self-deceptive illusory nature. Many of these come and claim to be the departed souls of relatives, acquaintances, well-known men, famous personalities, etc. There are also beings who pick up the discarded feelings and memories of the dead and masquerade with them. There are a great number of beings who come to such seances only to play with the consciousness of men or exercise their 
powers through this contact with the earth and who dope the mediums and sitters with their falsehoods, tricks and illusions. (I am supposing, of course, the case of mediums who are not themselves tricksters.) A contact with such a plane of spirits can be harmful (most mediums become nervously or morally unbalanced) and spiritually dangerous. Of course, all pretended communications with the famous dead of long-past times are in their very nature deceptive and most of those with the recent ones also – that is evident from the character of these communications. Through conscientious mediums one may get sound results (in the matter of the dead), but even these are very ignorant of the nature of the forces they are handling and have no discrimination which can guard them against trickery from the other side of the veil. Very little genuine knowledge of the nature of the after-life can be gathered from these seances; a true knowledge is more often gained by the experience of individuals who make serious contact or are able in one way or another to cross the border.