What Problems to Solve (1966)

> I have worked on innumerable problems that you would call humble, but which I enjoyed and felt very good about because I sometimes could partially succeed. For example, ... [list of many problems] ... Plus all the “grander” problems of quantum theory.

I'm having difficulty understanding what is meant here. Does he intend to say that his student thinks quantum theory is a humble problem?

I don't know what the student thinks but "[list of many problems]" are in some ways less "grand" as they are less about fundamentals of nature compared to the problems in quantum theory. But then Feynman puts "grander" in quotes to reduce its power and imply that "grandness" isn't all that - well - grand. He does this as his advice is that all problems for which you can find solutions are indeed grand problems. That's how I read it.

Part of the point here, IMHO, was to show that Feynman himself worked on numerous problems, even small ones, not just those he is famous for, and sometimes even failing to solve them.

My interpretation is that he is both meaning to say that getting where he is took a lot of patience and hard work, and also that it is on yourself to determine which problems are worth your time. Which are both very important insights to have if you don't want to feel miserable.