I have added nothing to what was already known. I have simply tried to separate what may be true from that which is assuredly not true; for, if we do not know where truth is, we nevertheless learn to know where it is not. And perhaps, in seeking for that undiscoverable truth, we shall have accustomed our eyes to pierce the terror of the last hour by looking it full in the face. Many things, beyond a doubt, remain to be said which others will say with greater force and brilliancy. But we need have no hope that any one will utter on this earth the word that shall put an end to our uncertainties. It is very probable, on the contrary, that no one in this world, nor perhaps in the next, will discover the great secret of the universe. And, if we reflect upon this even for a moment, it is most fortunate that it should be so. We have not only to resign ourselves to living in the incomprehensible, but to rejoice that we cannot go out of it. If there were no more insoluble questions nor impenetrable riddles, infinity would not be infinite; and then we should have for ever to curse the fate that placed us in a universe proportionate to our intelligence. All that exists would be but a gateless prison, an irreparable evil and mistake. The unknown and the unknowable are necessary and will perhaps always be necessary to our happiness. In any case, I would not wish my worst enemy, were his understanding a thousandfold loftier and a thousandfold mightier than mine, to be condemned eternally to inhabit a world of which he had surprised an essential secret and of which, as a man, he had begun to grasp the least tittle. VIII THE KNOWLEDGE OF THE FUTURE 1 What is known as premonition or precognition leads us to mysterious regions, where stands, half-emerging from an intolerable darkness, the gravest problem that can thrill mankind, the knowledge of the future. The latest, the best and the most complete study devoted to it is, I believe, that published by M. Ernest Bozzano under the title _Des Phénomènes prémonitoires_. Availing himself of excellent earlier work, notably that of Mrs. Sidgwick and Myers,[9] and adding the result of his own researches, the author collects some thousand cases of precognition, of which he discusses one hundred and sixty, leaving the great majority of the others on one side, not because they are negligible, but because he does not wish to exceed too flagrantly the normal limits of a monograph.