Note on teaching

I think everybody has heard the following famous quote from Abraham Lincoln:

"You can fool all the people some of the time, and some of the people all the time, but you cannot fool all the people all the time."

Today I suddenly found myself reflecting on all the different courses and lectures I've been to. The differences are huge: the best lectures have been phenomenal, whereas the worst ones have made me feel like I'd rather be deaf to avoid any similar experiences. I know the lecturers try their best, but teaching is really not that easy. It should be informative, compact and easy to understand. But still, the key ingredient is to not make it boring! So, I thought of an application of Lincoln. Maybe the golden rule of teaching should be instead

You can bore all the people some of the time, and some of the people all the time, but you cannot bore all the people all the time.