I'm going with ... not mine.
Lesson 1 - how can we change (ourselves/our work) if we're not informed? We can't.
Lesson 2 - If you are in the position to inform and you don't then you don't have much of a right to get cross and cranky.
Lesson 3 - Teach gently and with love then people don't get upset about things that don't change the course of the world and they might get fired up about things that do instead.
Class dismissed. (And steam vented!)