For two more summers Smith and Kilborne tramped about their fields, caulking up every seam in the ship of their research, answering every argument, devising astounding simple but admirably adequate answers to every objection the savant horse doctors might make--before these critics ever had a chance to make objections. They found strange facts about immunity. They saw northern calves get mild attacks of Texas fever, a couple of attacks in one summer maybe, and then next year, more or less grown up, graze unconcerned on fields absolutely murderous to a non-immune northern cow.... So they explained why southern cattle never die of Texas fever. This fell disease is everywhere that ticks are in the South--and ticks are everywhere; ticks are biting southern cattle and shooting the fatal queer pears into them all the time; these cattle carry the microbes about with them in their blood--but it doesn’t matter, for the little sickness in their calfhood has made them immune. Finally, after four of these stifling but triumphant summers, Theobald Smith sat down, in 1893, to answer all the perplexing questions about Texas fever--and to tell how the disease can be absolutely wiped out (just then the ancient Pasteur who had prophesied that about _all_ disease was getting ready to die). Never--and I do not forget the masterpieces of Leeuwenhoek or Koch or any genius in the line of microbe hunters--never, I say, has there been written a more simple but at the same time more solid answer to an enigma of nature. A bright boy could understand it; Isaac Newton would have taken off his hat to it. He loved Beethoven, did young Smith, and for me this “Investigation into the Nature, Causation, and Prevention of Texas or Southern Cattle Fever” has the quality of that Eighth Symphony of Beethoven’s sour later years. Absurdly simple in their themes they both are, but unearthly varied and complete in the working out of those themes--just as nature is at once simple and infinitely complex.... VII