"Why, I majored in philosophy in college," said Parker, hesitatingly. "But that's quite a time ago, Herr Doktor. Of course I've tried to keep up with the conclusions of science. But a writer or a painter doesn't have any too much opportunity. He has his own problems to concern him." "Yes, indeed!" Dr. von Stein was thoughtful. "So, and especially for the benefit of madame, I shall speak in terms of the concrete." "Please consider me stupid!" begged Betty. "But I want to understand!" "Certainly, except that you are not stupid, Madame. I will proceed. Both of you, I assume, know something of the radio? Very good! You know that an etheric wave transmits the message, and that it is received and amplified so that it is within the range of the human ear. These waves were there when paleolithic man hunted his meat with a stone-tipped club. To use them it was necessary to invent the microphone, and a receiving instrument. "What I have said you already know. But here is what may startle you. Human thought is an etheric wave of the same essential nature as the radio wave. They are both electrical currents external to man. Thoughts sweep across the human mind as sound currents sweep across the aerials of a radio--" "I told you!" Allen Parker turned a triumphant face to his wife. "Pardon me, Herr Doktor! I have tried to convince Mrs. Parker that my idea came from outside!" * * * * * "Exactly!" Dr. von Stein took no offense. "And a difference between the mind and the radio set is that with the radio you tune in upon whatever you choose, and when you choose. The mind is not under such control, although it should be. It receives that to which it happens to be open. Or that thought which has been intensified and strengthened by having been received and entertained by other minds. In India they say: 'Five thousand died of the plague and fifty thousand died of fear.' Do you both follow me?" It was unnecessary to ask. Betty sat on the edge of the couch, intent upon every word. Parker, although more restrained, was equally interested. Moreover he was delighted to have what he had felt instinctively confirmed, in a way, by a man of science. "Herbert Spencer said," continued the doctor, "that no thought, no feeling, is ever manifested save as the result of a physical force. This principle will before long be a scientific commonplace. And Huxley predicted that we would arrive at a mechanical equivalent of consciousness. But I will not attempt to bolster my position with authorities. I know, and I can prove what I know. "You, Mr. Parker, have been receiving some particularly annoying thoughts which have been intensified, it may be, by others, or another. Human will power can alter the rate of vibration of the line of force, or etheric wave. So-called good thoughts have a high rate of vibration, and those which are called bad ordinarily have a low rate. Have you, perhaps, an enemy?"