In this way those regions become to him matters of knowledge as definite, as certain, as familiar, as if he should travel to Africa in ordinary fashion, explore its deserts, and return to his own land the richer for the knowledge and experience gained. A seasoned African explorer would care but little for the criticisms passed on his report by persons who had never been thither; he might tell what he saw, describe the animals whose habits he had studied, sketch the country he had traversed, sum up its products and its characteristics. If he was contradicted, laughed at, set right, by untravelled critics, he would be neither ruffled nor distressed, but would merely leave them alone. Ignorance cannot convince knowledge by repeated asseveration of its nescience. The opinion of a hundred persons on a subject on which they are wholly ignorant is of no more weight than the opinion of one such person. Evidence is strengthened by many consenting witnesses, testifying each to his knowledge of a fact, but nothing multiplied a thousand times remains nothing. Strange, indeed, would it be if all the Space around us be empty, mere waste void, and the inhabitants of earth the only forms in which intelligence could clothe itself. As Dr. Huxley said: Without stepping beyond the analogy of that which is known, it is easy to people the cosmos with entities, in ascending scale, until we reach something practically indistinguishable from omnipotence, omnipresence, and omniscience.[17] If these entities did not have organs of sense like our own, if their senses responded to vibrations different from those which affect ours, they and we might walk side by side, pass each other, meet each other, pass through each other, and yet be never the wiser as to each other's existence. Mr. Crookes gives us a glimpse of the possibility of such unconscious co-existence of intelligent beings, and but a very slight effort of imagination is needed to realise the conception.