Bonus points if you guess the film this line is from!

What movie has this sentence been taken from? Comment below (if you know it).

What's a 'saga' in English? Can we say 'Harry potter' is a saga of books? On most sites it's called a series. Thank you

Today when I gave my students the class, I asked them to recite the translation of a very famous Chinese poem. At first, they thought it too difficult and reluctant to do it. I helped them to understand the poem sentence by sentence and recite sentence by sentence. In the end, most students participated actively and managed to recite the poem, which gave them a feeling of fulfillment. So I think it’s important for the teacher to figure out ways to let the students experience feelings of fulfillment. This in return will encourage them to work harder.

I'm wondering what's the difference between "be confident in oneself" and "be confident about oneself".I was told that I should say"there is no need to feel upset and discouraged when we are faced with failures.What is the most important is that we should be confident about ourselves."But I'm so confused that I don't understand why we must use "about" instead of "in".(>﹏<)