He begins by carefully eliminating all the episodes which, though apparently premonitory, may be explained by self-suggestion (as in the case, for instance, where some one smitten with a disease still latent seems to foresee this disease and the death which will be its conclusion), by telepathy (when a sensitive is aware beforehand of the arrival of a person or a letter), or lastly by clairvoyance (when a man dreams of the spot where he will find something which he has mislaid, or an uncommon plant, or an insect sought for in vain, or the unknown place which he will visit at some later date). In all these cases, we have not, properly speaking, to do with a pure future, but rather with a present that is not yet known. Thus reduced and stripped of all foreign influences and intrusions, the number of instances wherein there is a really clear and incontestable perception of a fragment of the future remains large enough, contrary to what is generally believed, to make it impossible for us to speak of extraordinary accidents or wonderful coincidences. There must be a limit to everything, even to distrust, even to the most extensive incredulity, otherwise all historical research and a good deal of scientific research would become decidedly impracticable. And this remark applies as much to the nature of the incidents related as to the actual authenticity of the narratives. We can contest or suspect any story whatever, any written proof, any evidence; but thenceforward we must abandon all certainty or knowledge that is not acquired by means of mathematical operations or laboratory experiments, that is to say, three-fourths of the human phenomena that chiefly interest us. Observe that the records collected by the investigators of the S. P. R., like those discussed by M. Bozzano, are all told at first hand, and that those stories of which the narrators were not the protagonists or the direct witnesses have been ruthlessly rejected. Furthermore, some of these narratives are necessarily of the nature of medical observations; as for the others, if we attentively examine the character of those who have related them and the circumstances which corroborate them, we shall agree that it is more just and more reasonable to believe in them than to look upon every man who has an extraordinary experience as being _a priori_ a liar, the victim of an hallucination, or a wag. 2