I knew that Dr. Brende had for years been one of the Earth's most eminent research physicians. It was he who discovered the light vibrations which had banished forever the dread germs of several of the major diseases. He did not practice; his work was research only. He went on: "Jac, I have found what for years I have been striving to find--a vibration of light, though it is invisible--which so far as I can determine, kills every bacillus harmful to man. There is nothing new in the idea--I have been working at it all my life. Sunlight! Altered and modified in several particulars, yet sunlight nevertheless. How strange that for countless centuries, man never realized the blessed boon of sunlight--the greatest enemy of all disease! "Each year, as you know, I have conquered some of what we call the major diseases. A few of them--cancer[5], for instance--persisted in eluding me. Its bacilli--you can easily recognize the tiny purplish, horned rods which cause what we popularly call cancer--just would not die. No form of light or other vibration I could devise, seemed to hurt them--unless I used a vibration harmful, even fatal, to the blood-contents itself: I killed the cancer--in the words of you news-gatherers--but I also killed the patient." [Footnote 5: A medical word, translated here as _cancer_, though possibly not that.] His eyes smiled at the jest, but his face remained intensely serious. "Then, Jac, I solved that problem--just a few months ago. And upon the heels of it I solved another, of infinitely more importance." He paused slightly. "I have learned how to kill, or at least arrest, the bacillus of old age. It is a bacillus, you know. We grow old because every day we live beyond the age of thirty--the bacillus of old age is attacking us. I call them the Brende-bacilli--these tiny, frayed discs that make us grow old. I have seen them--and killed them!" It dawned on me slowly, the import of what he was saying. "You mean----" "He means," said Georg, "that at present we cannot only banish disease--all disease--but we can keep your body from aging. Not permanently, doubtless--but with the span of life lengthened threefold at least. Only by violence now need you die prematurely." This then was the secret the existence of which Tarrano had learned. He had.... But Dr. Brende was quietly voicing my thoughts. "It seems obvious, Jac, that this Tarrano at least suspects that I have made some such discovery as this. That he would withhold it from mankind, for the benefit of his own race, seems also obvious. That he is about to make an attempt to get it from me, I am convinced." I remembered the wording of the message of warning from the Central State. _"Your Dr. Brende, in Eurasia."_ I mentioned it. "Our main laboratory is there," Georg said. "In Northern Siberia--isolated from people so far as possible, and in a climate advantageous for the work." Elza spoke for the first time in many minutes.