"If," said Gerald, "you had said these vibrations awakened the memories of the brain instead of the mind, I could have agreed with you. Yours are on the order of the London experiments. I am familiar with them, but only through reading." Again Virdow wondered, but he continued: "The powers of vibration are not understood--in fact, only dreamed of. Only one man in the world, your Keely, has appreciated its possibilities, and he is involved in the herculean effort to harness it to modern machinery. It was vibration simply that affected Gerald so deeply last night; a rhythm co-ordinating with his heart. I have seen vast audiences--and you have, too, Edward--painfully depressed by that dangerous experiment of Mendelssohn; for the heart, like a clock, will seek to adjust itself to rhythms. Your tempo was less than seventy-two to the minute; Gerald's delicate heart caught time and the brain lacked blood. A quick march would have sent the blood faster and brought exhilaration. Under the influence of march time men cheer and do deeds of valor that they would not otherwise attempt, though the measure is sounded only upon a drum; but when to this time is added a second, a third and a fourth rhythm, and the harmonies of tone against tone, color against color, in perfect co-ordination, they are no longer creatures of reason, but heroes. The whole matter is subject to scientific demonstration. "But back to this 'heart-beat march.' The whole nerve system of man since the infancy of the race has been subject to the rhythm of the heart, every atom of the human body is attuned to it; for while length of life, breadth of shoulders, chest measure and stature have changed since the days of Adam we have no evidence that the solemn measure of the heart, sending its seventy-two waves against all the minute divisions of the human machine, has ever varied in the normal man. Lessen it, as on last night, and the result is distressing. And as you increase it, or substitute for it vibrations more rapid against those myriad nerves, you exhilarate or intoxicate. "But has any one ever sent the vibration into that 'viewless vinculum' and awakened the hidden mind? As our young friend testifies, yes! There have been times when these lower co-ordinations of song and melodies have made by a momentary link mind and matter one, and of these times are born the world's greatest treasures--jewels wrested from the hills of eternity! What has been done by chance, science should do by rule." Gerald had listened, with an attention not hoped for, but the conclusion was anticipated in his quick mind. Busy with his portfolio, he did not attend, but upon the professor's conclusion he turned with a picture in his hand. It was the drawing of the previous night. "What is it?" he asked. "A mind picture, possibly," said Virdow. "You mean by that a picture never impressed upon the brain, but living within the past experience of the mind?" "Exactly."