Should we follow them? Should we each admit conditionally the spiritualist hypothesis? Not at all; it is not thus that knowledge is attained. Whoever believes that he has excellent reasons for preferring any other hypothesis should remain unshakable in his convictions till the time when new facts may oblige him to abandon them. Science does not ask that we should prefer this or the other explanation; it only asks that we should study the facts unprejudiced, that we should be sincere, and not shut our eyes childishly to the evidence. If a future life is to be, I will not say proved, but admitted by a majority, a great number of experimenters, or, if you please, observers, working independently of one another in all quarters of the globe, must reach identical conclusions. Again, it must be possible for any intelligent man willing to make the effort, and retracing the path followed by the first observers, to arrive at the same conclusions. The _magister dixit_ is out of date. Teachers in the present day must show their disciples the path of truth, and not try to impose upon them what they themselves regard as truth. Modern science knows no infallible Pope, speaking _ex cathedra_. Further, we must not confine ourselves to the study of one side of mediumship only. The phenomena produced in the presence of mediums are various. All the phenomena classified as "psychical" must be carefully considered and thoroughly investigated. The grain must be separated from the chaff; it must be decided which among these phenomena appear to be due to spirits, which, according to the evidence, are due to incarnated minds, and finally, which (if there are such) have only ordinary physical causes. The new workmen who are entering the field of science have before them a long task of clearing the ground, but the ground seems to be of unexampled fertility; with a very little goodwill we shall reap such a harvest as has never been seen. No doubt, though mediums able to produce certain second-rate phenomena are not rare, good mediums are not easy to discover; they are less rare, however, than the bones of _Anthropopithecus erectus_. When a good medium is discovered it is not necessary to call a committee together and put the value he may have for science to the vote. If the "other world" exists, it appears that no "missing link" exists between it and our own.