Paganini wrote musical scores for the violin, which no violinist has ever been able to play. Victor Herbert has recently analyzed some of these compositions and shown that Paganini himself could never have played them without using four hands and handling two bows at once. So far, no one can play a duet on the piano; the hand can span only so many keys, and the attempt of Robert Schumann to improve on Nature by building an artificial extension to his fingers was vetoed by paralysis of the members. Two bodies can not occupy the same space at the same time; mathematics has its limit, for you can not look out of a window four and a half times. The dictum of Ingersoll that all sticks and strings have two ends has not yet been disproved; and Herbert Spencer discovered, for his own satisfaction, fixed limits beyond which the mind can not travel. His expression, the Unknowable, reminds one of those old maps wherein vast sections were labeled, Terra Incognita. If we read Emanuel Swedenborg, we find that these vast stretches in the domain of thought which Herbert Spencer disposed of as the Unknowable have been traversed and minutely described. Swedenborg's books are so learned that even Herbert Spencer could not read them: his scores are so intricate, his compositions so involved, that no man can play them. The mystic who sees more than he can explain is universally regarded as an unsafe and unreliable person. The people who consult him go away and do as they please, and faith in his prophecies weaken as his opinions and hopes vary from theirs. We stand by the clairvoyant just as long as he gives us palatable things, and no longer, and nobody knows this better than your genus clairvoyant. When his advice is contrary to our desires, we pronounce him a fraud and go our way. When enterprises of great pith and moment are to be carried through, we give the power into the hands of the worldling infidel, rather than the spiritual seer. The person on intimate terms with another world seldom knows much about this, and when Robert Browning tells of Sludge, the Medium, he symbols his opinion of all mediums. A medium, if sincere, is one who has abandoned his intellect and turned the bark of reason rudderless, adrift. This is entirely apart from the very common reinforcement of usual psychic powers with fraud, which, beginning in self-deception, puts out from port without papers and sails the sea with forged letters of marque and reprisal. There are mediums in every city who tell us they are guided by Shakespeare, Dante, Milton, Luther, Tennyson or Henry Ward Beecher. So we are led to believe that the chief business of great men in the spiritual realm is to guide commonplace men in this, and cause them to take pen in hand.