Tom posted a link to an interview Richard Feynman gave the BBC in 1981. I especially like this statement of Feynman about living with doubt:
You see, one thing is, I can live with doubt and uncertainty and not knowing. I thinks it’s much more interesting to live not knowing than to have answers which might be wrong. I have approximate answers and possible beliefs and different degrees of certainty about different things, but I’m not absolutely sure of anything and there are many things I don’t know anything about, such as whether it means anything to ask why we’re here, and what the question might mean.
I might think about it a little bit and 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 a mysterious Universe without having any purpose, which is the way it really is so far as I can tell. It doesn’t frighten me.
Have a nice day. I will, because I’m on vacation 