"Our philosophers," he answered, "are probably satisfied that they know nearly all that is to be known of natural laws and forces; and to delusion or illusion human sense is undeniably liable." "If," I said, "you cannot trust your senses, you may as well disbelieve in your own existence and in everything around you, for you know nothing save through those senses which are liable to illusion. But we know practically that there are limits to illusion. At any rate, your maxim leads directly and practically to the inference that, since I do not belong to Mars and cannot have come from any other world, I am not here, and in fact do not exist. Surely it was somewhat illogical to shoot an illusion and intend to dissect a spectre! Is not a fact the complete and unanswerable refutation of its impossibility?" "A good many facts to which I could testify," he replied, "are in this world confessed impossibilities, and if my neighbours witnessed them they would pronounce them to be either impostures or illusions." "Then," said I, somewhat indignantly, "they must prefer inferences from facts to facts themselves, and the deductions of logic to the evidence of their senses. Yet, if that evidence be wanting in certainty, then, since no chain can be stronger than its weakest point, inferences are doubly uncertain; first, because they are drawn from facts reported by sense, and, secondly, because a flaw in the logic is always possible." "Do not repeat that out of doors," he answered, smiling. "It is not permitted here to doubt the infallibility of science; and any one who ventures to affirm persistently a story which science pronounces impossible (like your voyage through space), if he do not fall at once a victim to popular piety, would be consigned to the worse than living death of life-long confinement in a lunatic hospital." "In that case I fear very much that I have little chance of being put under the protection of your laws, since, whatever may be the impression of those who have seen me, every one else must inevitably pronounce me non-existent; and a nonentity can hardly be the subject of legal wrong or have a right to legal redress." "Nor," he replied, "can there be any need or any right to annihilate that which does not exist. This alternative may occupy our Courts of Justice, for aught I know, longer than you or I can hope to live. What I have asked is that, till these have decided between two contradictory absurdities, you shall be provisionally and without prejudice considered as a human reality and an object of legal protection." "And who," I asked, "has authority _ad interim_ to decide this point?"