The idea that progress is not linear. The notion that life presents all sorts of unexpected (and even all sorts of predictable) obstacles.
Weird that this is the case.
That one hopes for something is one thing. That one accepts doubt as a fixture of reality is another. It appears to be hard for people to do both at the same time, as if they breathe the same oxygen and one or the other must die.
I find considering alternative possibilities to be instructive. They provide perspective. And yet it is clear that this kind of thinking, which to me is the essence of imagination, seems a threat to others.