We acquire new knowledge every time we walk into the classroom. When we hold what we know up to the lens of student curiosity it changes. We leave the classroom with our knowledge altered and renewed because a process has occurred. The classroom is also central to the preservation of knowledge. In the classroom we see, more and more clearly, what part of knowledge is gold and what part is dross.
Teaching is where preservation begins.
Preservation continues with the students themselves. Surely the most important way we preserve knowledge is to embed it in successive generations. We do not. That suggests we plow over ground that other people have tilled. Actually, research does involve reworking.