Hey, I think it was a pretty obvious idea. In high school, preparing for physics exams, rather than memorising all the formulas, I worked on figuring them out based on some root principles, on the fly. So every exam I spent the first 10 minutes reading the exam and deriving all the formulas I gathered I needed on the back of the answer booklet. It was a lot more effective than memorising which type of questions needed which formula.<p>Like maybe 15 years ago my dad wanted to teach me maths and he kept repeating the importance of learning the &#x27;first principles&#x27;. I didn&#x27;t get a word he was saying at the time, but looking back, he had the idea too.