The aphorism you quoted isn't the advice. Feynman's advice was not to be ashamed to work on problems that you feel you can make progress on, however "humble" t

The aphorism you quoted isn't the advice. Feynman's advice was not to be ashamed to work on problems that you feel you can make progress on, however "humble" they are, because those are the kind where your work matters. I think that's much more specific and insightful. Also, his closing remarks have a lot more weight if you take in them in the context of being directly addressed from the teacher in question to the former naive, idealistic student.