First, assuming that the spirits live forever, there are some useful things which were known to the people of ancient time, and are not known to anyone living now. For example, let one of the Egyptian craftsmen come forward and tell us the secret of their glass-staining, which I understand is now a lost art. And then Sophocles, as I have already suggested, will tell us where we can find his lost dramas; or if he doesn't know where any copies are buried, let him find in the spirit world some scribe or librarian or book-lover who can give us this priceless information. All over the ancient lands are buried and forgotten cities, and in those cities are papyrus scrolls and graven tablets and bricks. Infinite stores of knowledge are thus concealed from us; and how simple for the ancient ones who possess this information to make it known to us, and so to convince us of their reality! Or, again, supposing that spirits are not immortal, but that they slowly fade from life as do their bodies. Suppose that a Raymond Lodge or other recently dead soldier wishes to communicate with his father and to convince his father that it is really an independent being, and not simply a part of the father's subconscious mind--let him try something like this. Let the father write six brief notes, and put them in six envelopes all alike, and shuffle them up and put them in a hat and draw out one of them. Now, assuming that the experimenter is honest, there is no living human being who knows the contents of that envelope, and if the medium is dipping into the subconscious mind of the experimenter, the chances are one in six of the right note being hit upon. Assuming that spirits may not be able to get inside an envelope and read a folded letter, there is no objection to the experimenter, provided he is honest, and provided there are no mirrors or other tricks, holding the envelope behind his back, and tearing it open, and spreading it out for the convenience of the spirit. And now, if the spirit can read that letter correctly every time, we shall be fairly certain that whatever force we are dealing with, it is not the subconscious mind of the experimenter. Or, let us take another test. Let us have a roulette wheel in a covered box, or hidden away so that no one but the spirit can see it. We spin the wheel, and any one of the habitues of Monte Carlo can figure out the chance of the little ball dropping into any particular number. If now the spirit can tell us each time where we shall find the ball, we shall know that we are dealing with knowledge which does not exist either in the conscious or the subconscious mind of any living human being.