If we will only allow that, as we progress, we remain unsure, we will leave opportunities for alternatives. We will not become enthusiastic for the fact, the knowledge, the absolute truth of the day, but remain always uncertain.

More from Richard Feynman

• I can live with doubt and uncertainty and not knowing. I think it is much more interesting to live not knowing than to have answers that might be wrong.
• If we want to solve a problem that we have never solved before, we must leave the door to the unknown ajar.
• I was born not knowing and have only had a little time to change that here and there.
• The truth always turns out to be simpler than you thought.