|Ruination IPA by Stone|
I used to tell residents that most of the time, the diagnosis is something common, or something related to something we already know the patient has. In addition, when teaching history taking, I told the medical students to view history taking as an exercise in determining what the patient is exposed to in his or her environment, for these exposures weigh on the probabilities of potential diagnoses. These principles explain the basis of the history aphorism.
Nassem Nicholas Taleb was right in his book Antifragile - evolution has made our species beyond robust - antifragile, a term which he coined. We resist disease, we repair injury, we get stronger when exposed to stress (the antifragile principle). But there are ailments that humans suffer for which evolution has not worked out a defense or a solution, or those which result because evolution is helping the same organisms which attack us become antifragile just as it selects us for antifragility. This is why infectious maladies are at the top of the list for adult (and I suspect pediatric) internal medicine admissions. Pneumonia, UTI, URI, etc.