Richard Feynman on doubt and uncertainty:
You see, one thing is I can live with doubt, uncertainty and not knowing. I think it's much more interesting to live not knowing then to have answers which might be wrong.
I have approximate answers and possible believes and different degrees of certainty about different things, but I'm not absolutely sure about anything and many things I don't know anything about. Whether it means anything to ask, why we're here. What that question might mean? I might think about it a bit. If I can't figure it out, then I go on to something else.
But I don't have to know an answer. I don't feel frightened by not knowing things. By being lost in the mysterious universe without having any purpose, which is the way it really is, as far I can tell, possibly.
It doesn't frighten me.