It was a profound insight of the sort that comes from witnessing loss and suffering up close. (As the chronically ill know, to be alive is to be in uncertainty.) I was grateful for his words, because they reminded me that I wasn’t living off the known map of human experience. Rather, I had felt invisible in my illness, I realized, because American culture—and American medicine within it—largely strives to downplay the fact that we still know so little about illness.