159. Everyone who is in any degree influenced by spirits is, by that very fact, a medium. This faculty is inherent in man, and is therefore no exclusive privilege; in fact, there are few persons in whom some rudiments of medianimity are not found. We may therefore assume that everyone, or nearly everyone, is a medium. Nevertheless, this qualification is only practically applicable to those in whom the medianimic faculty is clearly characterised, producing well-marked results and this depends upon the greater or less degree of sensitivity of the organisation. This faculty does not reveal itself in all cases in the same manner: each medium has generally a special aptitude for some special order of phenomena; so that there is as great a variety of mediums as of phenomena. The principal varieties of mediums are as follows: Physical mediums; Sensitive or Impressionable mediums; Hearing mediums; Speaking mediums; Seeing mediums; Somnambulists; Healing mediums; Pneumatographers; Writing mediums, or Psychographers.