And what was the cause of these things? So far as we can see, the material cause was exactly the same in each case--the reading of certain letters. Two human beings, sitting side by side and reading exactly the same letters, might be affected in exactly opposite ways. It seems hardly rational to maintain that the material difference of two pairs of eyes, moving over exactly the same set of letters, could have resulted in two such different motions of the hands. As a matter of fact, the very same letters may affect the same person in different ways. The composer, Edward MacDowell, once told me how on his birthday his pupils sent him a gift, with a card containing some lines from the opera "Rheingold," beginning, "O singe fort"--that is, "Oh, sing on." But the composer happened, when glancing at the card, to think French instead of German, and got the message, "Oh, powerful monkey!" This, of course, was disconcerting to a famous piano performer, and his pupils, if they had been watching his face, would have seen an unexpected reaction. It seems manifest, does it not, that the cause of this difference of reaction was not any difference of the letters, but purely a difference of _thought_? So it appears that thoughts may change the material universe; they may break the chain of causation, and interfere with material events. Compare the two things, a state of consciousness and say, a steam shovel. They are entirely different, and so far as we can see, entirely incompatible and unrelated. Can anyone imagine how a thought can turn into a steam shovel, or a steam shovel into a thought? We can understand how a steam shovel lifts a mass of earth out of the ground, and we can understand how a human hand moves a lever which causes the shovel to act; but we are unable to conceive how a state of mind--whether it be a desire for pay, or an ideal of service, or a vision of the Panama Canal--can so affect a steam shovel as to cause it to move. We can sit and think motion at a billiard ball for a thousand years, and it does not move; but when we think motion at our hand, it moves instantly, and passes on the motion to the billiard ball or the steam shovel. When fire touches our hand it sends some kind of vibration to the brain, and in some inconceivable way that vibration is turned into a state of consciousness called pain, and that is turned, "as quick as thought," into another kind of motion, the jerking back of our hand.