Rich Or Poor?

A story about a teacher who is giving out his last teaching to the soon-to-be-graduating students. Unexpectedly, the teacher has also learn a new thing that is very shocking and will definitely leaves an impact to the old teacher greatly.
The main idea about this story is simple that is everyone regardless of age will use their lifetime to learn. Also, everyone have different kind of lives which we may or may not imagine. therefore, it is near impossible for us to categorizes everyone in the world.