This reality was powerfully demonstrated in the 1920s by a medical doctor, Francis Pottenger. He was not gifted with a good bedside manner. Rather than struggling with an unsuccessful clinical practice, Dr. Pottenger decided to make his living running a medical testing laboratory in Pasadena, California. Dr. Pottenger earned his daily bread performing a rather simple task, assaying the potency of adrenal hormone extracts. At that time, adrenaline, a useful drug to temporarily rescue people close to death, was extracted from the adrenal glands of animals. However, the potency of these crude extracts varied greatly. Being a very powerful drug, it was essential to measure exactly how strong your extract was so its dosage could be controlled. Quantitative organic chemistry was rather crude in those days. Instead of assaying in a test tube, Dr. Pottenger kept several big cages full of cats that he had adrenalectomized. Without their own adrenals, the cats could not live more than a short time By finding out how much extract was required to keep the cats from failing, he could measure the strength of the particular batch. Dr. Pottenger's cats were economically valuable so he made every effort to keep them healthy, something that proved to be disappointingly difficult. He kept his cats clean, in airy, bright quarters, fed them to the very best of his ability on pasteurized whole milk, slaughterhouse meat and organs (cats in the wild eat organ meats first and there are valuable vitamins and other substances in organ meats that don't exist in muscle tissue). The meat was carefully cooked to eliminate any parasites, and the diet was supplemented with cod liver oil. However, try as he might, Pottenger's cats were sickly, lived short and had to be frequently replaced. Usually they bred poorly and died young of bacterial infections, there being no antibiotics in the 1920s. I imagine Dr. Pottenger was constantly visiting the animal shelter and perhaps even paid quarters out the back door to a steady stream of young boys who brought him cats in burlap sacks from who knows where, no questions asked. Dr. Pottenger's assays must have been accurate, for his business grew and grew. Eventually he needed more cats than he had cages to house, so he built a big, roofed, on-the-ground pen outdoors. Because he was overworked, he was less careful about the feeding of these extra animals. They got the same pasteurized milk and cod-liver oil, but he did not bother to cook their slaughterhouse meat. Then, a small miracle happened. This poorly cared for cage of cats fed on uncooked meat became much healthier than the others, suffering far fewer bacterial infections or other health problems. Then another miracle happened. Dr. Pottenger began to meditate on the first miracle.