If stillborn children could inspire one of the most-loved children’s books in the twentieth century, then maybe a grandpa with dementia will inspire one of the best stories in the twenty-first. 
Keeping the person at the center of concern maintains our focus on his or her good rather than on our own fears and insecurities. And, each time we practice accepting another in the fullness of their fragility, we come to a healthier, more honest acceptance of ourselves, too.  
Today we might instinctively look at Nazi criteria for death as utterly baseless, but at the time seasoned medical professionals regarded them as reasonable. To have a sense of history is to grasp the arbitrariness of such criteria. When it comes to killing patients, there is no way to get the criteria just right because the stamp of medical approval sends a social message that there is a category of persons who should not exist.