On top of being one of the greatest physicists of the 20th century CE, Feynman was a brilliant teacher. He presented complex ideas in elementary terms. Of course, one needed bring intelligence to the table. Best if one had an infinite amount of intelligence when it came to understanding the most elementary ideas.
“I am going to give what I will call an elementary demonstration. But elementary does not mean easy to understand. Elementary means that very little is required to know ahead of time in order to understand it, except to have an infinite amount of intelligence.”