I do not propose to consider here whether psychical research has yet given any satisfactory answer to the above mentioned questions or even whether there is any considerable chance of its ever being able to do so. I merely wish to point out the nature of the problems with which it is concerned and which alone distinguish it as a separate science. It follows that any hypothesis advanced with a view to co-ordinating the observed facts _may_ find itself called upon to give an intelligible explanation of discarnate personalities, that is to say of human personalities not functioning through the flesh and blood bodies in which we are accustomed to meet them. So far as our present knowledge goes and on the balance of all the available evidence I am inclined to think that this necessity is at least imminent. The adoption of some form of working hypothesis is moreover imperative in the light of scientific history. All who are interested in psychical research will agree that it is in the highest degree desirable that it should be recognised as a Science of a dignity commensurate with its intrinsic importance and on a level with the sciences more generally accepted as such. That it has not, hitherto, attained this position in the eyes of the world in general is largely due to the fact that it has not yet fully reached that stage of development which chiefly distinguishes a science properly so called from mere speculatory observation. This is no reflection on the many able and genuinely scientific men who have worked on the subject ever since it first became prominent in modern times some seventy years ago but is, on the contrary, a necessary and inevitable stage in the growth of any science whatsoever. The processes of acquiring scientific knowledge are as invariable as those of logical thought. Just as all accurate reasoning may be reduced to a series of syllogisms, so the process of acquiring exact knowledge may be reduced to a series of analogous sequences. These are:--(1) Observation. (2) Induction. (3) Deduction. (4) Experiment.--A special form of observation. I do not say that this sequence of operations is always consciously performed any more than when "thinking a thing out" we always consciously reduce our reasoning to its simplest syllogistic constituents. But every time we acquire a new item of knowledge it would be possible to reduce the process by which we acquired it to a series of the sequences mentioned above. It is worth while considering these steps in slightly greater detail. OBSERVATION in the last analysis means no more than the recording and classifying of sensations, which are the only form in which we get any information as to the outer world.