If we were to lose our fish that we appreciate so much by overfishing; or if we were to lose some of our favorite beaches to overbuilding and pollution, then how would we feel? It's become a case of not knowing what you've got until it's gone.
The most strongly enforced of all known taboos is the taboo against knowing who or what you really are behind the mask of your apparently separate, independent, and isolated ego.
The physician himself, if sick, actually calls in another physician, knowing that he cannot reason correctly if required to judge his own condition while suffering.