"Medical knowledge has grown so vast, no single human can know it all - no matter how much experience they have, no matter how many patients they've seen, and no matter how many textbooks they've read, no matter how many journals they keep up with. Some classes of cognitive errors are rooted in this limitation - you can't see what you dont' know what to look for. And even if you know about an illness, you may not think of it if a patient presents with an unusual version of the disease "