A Concept I have thought about is corporate knowledge. That is the knowledge of every person alive combined, the "Corporate body of man". As a person grows he is acquiring a little piece of the knowledge. Everything he sees learns and experiences is part of that knowledge. When a person dies that piece of the knowledge is lost.
The job of the teacher is pass on the knowledge he has to keep it for the future. My father had a brilliant mind and was continuing to invent and share his ideas until his death last year in a stupid accident at the age of almost 92. How much was Lost?