_Reciprocal._--Used of cases where there is both agency and percipience at each end of the telepathic chain, so that A perceives P, and P perceives A also. _*Retrocognition._--Knowledge of the past, supernormally acquired. _Secondary personality._--It sometimes happens, as the result of shock, disease, or unknown causes, that an individual experiences an alteration of memory and character, amounting to a change of personality, which generally seems to have come on during sleep. The new personality is in that case termed _secondary_, in distinction to the original, or _primary_, personality. _Secondary sensations_ (_Secunddrempfindungen_, _audition colorée_, _sound-seeing_, _synæsthesia_, _etc._).--With some persons every sensation of one type is accompanied by a sensation of another type; as for instance, a special sound may be accompanied by a special sensation of colour or light (_chromatisms_ or _photisms_). This phenomenon is analogous to that of _number-forms_,--a kind of diagrammatic mental picture which accompanies the conception of a progression of numbers. See Galton's _Inquiries into Human Faculty_. _Shell-hearing._--The induction of hallucinatory voices, etc., by listening to a shell. Analogous to crystal-gazing. _Stigmatisation._--The production of blisters or other cutaneous changes on the hands, feet, or elsewhere, by suggestion or self-suggestion. _Subliminal._--Of thoughts, feelings, etc., lying beneath the ordinary _threshold_ (_limen_) of consciousness, as opposed to _supraliminal_, lying _above_ the threshold. _Suggestion._--The process of effectively impressing upon the subliminal intelligence the wishes of some other person. _Self-suggestion_ means a suggestion conveyed by the subject himself from one stratum of his personality to another, without external intervention. _*Supernormal._--Of a faculty or phenomenon which transcends ordinary experience. Used in preference to the word _supernatural_, as not assuming that there is anything outside nature or any arbitrary interference with natural law. _Supraliminal._--See _Subliminal_. _Synæsthesia._--See _Secondary Sensations_. _Synergy._--A number of actions correlated together, or combined into a group. _Telekinesis._--Used of alleged supernormal movements of objects, not due to any known force. _*Telepathy._--The communication of impressions of any kind from one mind to another, independently of the recognised channels of sense. _*Telæsthesia._--Any direct sensation or perception of objects or conditions independently of the recognised channels of sense, and also under such circumstances that no known mind external to the percipient's can be suggested as the source of the knowledge thus gained. _*Telergy._--The force exercised by the mind of an agent in impressing a percipient,--involving a direct influence of the extraneous spirit on the brain or organism of the percipient.