The Value of Books in Lean

What is the Value of Books in Lean?

I was asked in this newsletter to address the value of books in Lean.  Although it seems like an easy question the more I thought about the question the more it became apparent that we need to consider what value is.  For something to be valuable do we not need to compare it against something else?  Well, to keep it simple I think this is a fair statement.  Now Plato may have an issue with this and the idea of the Meno problem, but we will keep that to another day and epistemology debate.  What I can say is that books play an important role in helping us discover, and also provide tools to achie