I think what feynman says in this kind of matter is very important. Understanding is more important than just knowing information. Once you understand things, it's not hard. You just need to invest time. For example, if you can't explain relativity to a 3rd grader you don't really understand it either. I really recommend watching "What do you care what other people think" series on youtube (side note: he does talk a bit about his love life but things that are said there have their meaning). He explains that for example our languages like english is just a human convention. This really hit me. Math notations are used so extensively (I understand the importance of them) but when you want an understanding, you have to interpret it in your own way. If you know the formal definition of derivative but cannot understand why and how it's applicable (for example to derive equations you once had to remember in high school!) then it's not very useful.

The one who has an open mind to think of all the posibilities of why things are the way they are (by eliminating the wrong choices) is the one who masters the topic and possibly even discover new things. [Twist: Everything we know is just an approximation, they're not accurate; But that's for another day, also by Feynman btw].