During the course of my twenty years' constant investigation, I have had many score seances with various mediums--slate-writing mediums, materializing mediums, physical mediums, clairvoyant mediums, _et hoc genus omne_. Speaking now of materialization seances only--of which I have seen many--I may say that in all my investigations _I have never seen one single instance of suggested or spontaneous hallucination_. Plenty of _illusions_ were observed, but never the trace of a full-blown hallucination.[35] And I venture to think that, if we examine the evidence in the case of D. D. Home, we find very few cases which could have been illusions--the vast majority of them seem to have been "pure hallucinations"--if they were psychological processes (as opposed to physical) at all. So that we should have to suppose that we find in these seances--not mere illusions, commonly seen at spiritualistic seances, but full-blown hallucinations of a type rarely or never seen elsewhere. In other words, these seances present evidences of psychological processes for which we can find no analogy in any other series of seances, or in hypnotic or any other phenomena with which we are familiar. I venture to think that this entirely _new_ order of things cannot be accepted upon such evidence: that the hypothesis of hallucination cannot be said to explain anything whatever, inasmuch as it is entirely unsupported by facts, and finds no analogies whatever in any other psychological processes known to us.