Zen students are with their masters at least ten years before they presume to teach others, after all learning all one can isn't as easy as learning how to ask a girl out or how to ride ones bicycle. These are lessons that take the span of a decade to master. Nan-in was visited by Tenno, who, having passed his apprenticeship, had become a teacher. The day happened to be rainy, so Tenno wore wooden clogs and carried an umbrella. After greeting him Nan-in remarked: "I suppose you left your wooden clogs in the vestibule. I want to know if your umbrella is on the right or left side of the clogs."
Tenno, confused, had no instant answer . He realized that he was unable to carry his Zen every minute. He became Nan-in's pupil, and he studied six more years to accomplish his every-minute Zen.
I would like to start this post out by saying, I am not a Buddhist. I do meditate from time to time and that anything inferred from this koan is coming from the lens of a western mind. It is not beneficial to differing societies if they do not -- at least -- attempt to see the others' perspective through a lens of their own making. Sometimes the lens needs refocusing. Sometimes the interpretation is spot-on.
It is impossible for you to control the entire world. As children, we take the world in as it is. As teens, we mold it piece-by-piece to our desires. As adults, we watch what we had sewn as teens, unfold before us. Then, we start blaming ourselves for the way it unfolded. We start to tell others how they must change their very lives to avoid the mistakes which we have made. We go into an automation state involving a single cause always leading to a single effect.
The problem with this thinking is, we've forgotten where we placed our clogs during the cause. Causes are made of many tiny details. Your clogs just might be one of those details. Do you remember where your clogs were when you made your mistake as a teen? Do you remember exactly what you were doing? If not, are you buying into the notion that society is feeding you, that this cause will always lead to a certain effect?
If you can't remember where your clogs were, instead of criticizing the situation as always being a failure, watch the person's decision and note what exactly it is, in the situation, they're doing wrong. Then demonstrate to them how they could do it better. We learn by example, not by instruction. The finest teacher in the world could give the finest lecture and every student in his class come out not knowing what he was saying.