This is incredibly well explained. Everything is simple, yet it is packed with so much details that memorising this and understanding this cannot be done without effort and focus. This whole stuff is fascinating when explained in such a way that it makes sense. I fought with this during my 2nd year of engineering studies, but did certainly not understand half of it at the time. With that explanation, I would have enjoyed studying the subject so much more. I guess I was not smart enough to understand my textbook and all the consequences of the formulas, so that I was unable to be fascinated by the subject.